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In 1651, Harvey published the concept that all living things originate from eggs.  Harvey believed that in principle organisms could be spontaneously generated, and that the process was the self-generation of a complicated machine.

In 1651, Thomas Hobbes, in Leviathan, argued from a mechanistic theory that man is a selfishly individualistic animal at constant war with others.  In the state of nature, life is "nasty, brutish, and short."
In 1652, Thomas Bartholin discovered the lymphatic system and determined its relation to the circulatory system.

In 1654, Otto von Guericke removed the air from within two metal hemispheres.  Teams of horsemen were challenged to pull them apart, which they failed to do.

[In 1654, James Ussher, Protestant archbishop of Armagh, determined by a close reading of scriptural genealogies that the events described on the first page of the Book of Genesis occurred in 4004 B.C.]

In 1654, William Petty, working on Irish estates confiscated by Oliver Cromwell, carried out the first large scale attempt at a scientific survey.

In 1655, Christiaan Huygens discovered 'Titan,' Saturn's largest moon, and that what Galileo had thought were moons were actually rings.  He was the first to note markings on Mars.  He also applied Galileo's idea that a falling body does so in a straight line to planetary orbits, calculating "the radial force necessary to keep a planet in a circular path [is] mv2/r, where m is the mass, v the velocity, and r the orbital radius" (Grosser 1979:9).

In the mid-1650s, Thomas Sydenham promoted the idea that diseases were organisms inside a host.  He advocated direct observation and classification to determine the nature of disease, and introduced quinine and laudanum to English medicine.

In 1656, John Wallis, in Opera mathematica, made the transition from the geometry of lines to the arithmetic of numbers where he made the first use of the category 'infinity' in the field of arithmetic and invented its symbol.

In 1656, Huygens built the first pendulum-regulated clock.  Two years later, Huygens, in Horologium, claimed that his clock could establish longitude at sea which was not then possible and had led to many maritime disasters.  This claim was not borne out.

In 1657, Fermat stated the 'least time' principle according to which a light ray follows the path to its destination in the shortest possible time.

In 1657, Huygens wrote the first textbook on probability, Calculating in Games of Chance.

In 1658, Henry More, in Immortality of the Soul, argued "the first primary matter must be atoms and that matter may be so small as to be indiscernible" (Newton, quoted in White 1997:55).

In 1659, Pascal, in Traité des sinus du quart de cercle, used the language of infinitesimals when writing of the sum of all the ordinates.  In De l'esprit géometric, he held that in numbers the infinitely large and the infinitely small are complementary.

In 1661, Marcello Malpighi, in De pulmonibus, reported his observation of blood movement through the capillaries.  He is also noted for his studies of the glands.

In 1661, Robert Boyle, in the Sceptical Chymist, separated chemistry as corpuscles, from alchemy, as qualities, and gave the first precise definitions of a chemical element, a chemical reaction, chemical analysis, and made studies of acids and bases. It was only after this that scientists generally abandoned the ancient notion that matter was compounded of 'Fire, Earth, Air, and Water.'

In 1662, Boyle, using a vacuum pump of his own invention, determined that the volume and pressure of a gas are inversely proportional.  This is known as 'Boyle's law.' He also determined that sound doesn't travel in a vacuum.

In 1662, Antoine Arnauld and others contributed to a book known as the Port Royal Logic, or the Art of Thinking, where the question was first taken up of the two sorts of non-deductive reasoning, inference and decision under uncertainty, on the one hand, and theorizing, or what Charles Sanders Peirce later called 'abduction,' on the other.

Beginning in 1662, Isaac Barrow lectured on geometry.  The results of his investigations include many theorems on tangents and quadratures and an atomistic conception of a line: "Time has many analogies with a line...; for time has length alone, is similar in all its parts, and can be looked upon as constituted from a simple addition of successive instants or as a continuous flow of one instant" (Barrow 1662:37).  All of his propositions were cast in geometric forms which Newton, his student, recast in the analytic symbolism of Fermat, Descartes, and Wallis.

In 1662, John Graunt, in Observations upon the Bills of Mortality, using London population data, noted that life expectancy is 27 years, with nearly two/thirds dying before 16 years.

In 1663, James Gregory, in Optica Promota, described the reflecting telescope which he had built and which used a convergent mirror as its object in order to cure aberrations.

In 1664, Thomas Willis, in Cerebri anatome, identified the corpus striatum, now called the basal ganglia, as the initiator of motor acts as well as being the receiver of sensory data. and distinguished the cortical gray matter from the deeper white matter. He also abandoned Galen's doctrine of the ventricles and gave primacy to the cerebral cortex.  [revised 02/01/03]

In 1665, Francesco Maria Grimaldi, in Physico-Mathesis de lumine, coloribus, et eride, published posthumously, discovered that light going through a fine slit cannot be prevented from spreading on the farther side, a phenomena which he named 'diffraction' and postulated was caused by its wave-like motion.  

In 1665, Robert Hooke, in Micrographia, named and gave the first description of cells. He also described plant and animal fossils, comparing their microscopic structure to that of living organisms. Hooke also noted the 'black spot' in soap bubbles, and, independently of Grimaldi, hypothesized that light is "a 'very short vibrative motion' transverse to straight lines of propagation through a 'homogenous medium.'  Heat [is] defined as 'a property of a body arising from the motion or agitation of its parts'" (Koyré 1965:223n2).

In 1665, Gian Domenico Cassini, while attempting to map Jupiter, discovered the Great Red Spot, an area about 48,000 by 11,000 kilometers that drifts across the planet's south temperate zone.

By 1666, Newton had discovered the essentials of calculus, the law of universal gravitation, and that white light is composed of all the colors of the spectrum.

In 1668, Francisco Redi described a series of experiments which showed that the maggots in meat were the larva of flies.

In 1668, Cassini published an ephemerides of great accuracy and included the rotational periods of Jupiter, Mars, and Venus.  This won him the directorship of the Paris observatory the following year where both Huygens and Olaus Roemer worked under him.

In 1669, Newton circulated a manuscript, De analysi per aequationes numero terminorum infinitas, the first notice of his calculus, which gave "a generally applicable procedure for determining an instantaneous rate of change and to invert this in the case of problems involving summations" (Boyer 1949:192).  A more extensive exposition of the calculus, Methodus fluxionum et serierum infinitarum, with the introduction of his characteristic terminology, was available in manuscript about two years later.  The former was not published until 1711; the latter, 1736.

In 1669, Nils Steensen, known as Steno, by postulating a sequence of distinct geological phases, was able to explain how land acquired its current conformation: E.g., marine fossils indicate a former sea bed, which was violently uplifted, and, afterward, undermined by subterranean forces, causing the strata to breakup, become eroded, and, in due course, form another sea bed.

In 1670, Boyle produced hydrogen by reacting metals with acid.

In 1670, the editors of the Port Royal Logic published Pascal's Pensées, eight years after his death.  In it, he discusses probabilty in terms of a wager on the existence of God: If God exists, wagering that he doesn't brings damnation and that he does brings salvation.  Since salvation is better than damnation, 'God exists' dominates the wager.

Between 1671 and 1684, Cassini discovered four of Saturn's moons and studied the division in its ring system that bears his name.  Also, in 1671, he made the first successful measurement of the parallax of Mars in an effort in which Jean Richer led an expedition to Guiana in order to create a base sufficient for the triangulation.

In 1672, More, in Enchiridium metaphysicum, asserts "the real existence of infinite void space...as a real precondition of all possible existence [and] as the best and most evident example of non-material--and therefore spiritual--reality and thus the first and foremost...subject-matter of metaphysics" (Koyré 1957:137).  More had taught Newton in his first years at Cambridge ten years earlier

About 1674, Hennig Brand discovered phosphorus in a distillation of human urine.

In 1674, Nicolas Malebranche elaborated the conception that each embryo is encased in the embryo of its parent.
In 1674, Anton van Leeuwenhoek reported his discovery of protozoa. [added 02/01/03]

In 1675, Nicolas Lémery published a chemistry textbook in which he espoused the corpuscle theory.

In 1676, Nehemiah Grew suggested the true nature of ovules and pollen.

In 1676, Roemer proved that light travels at a finite speed by repeated observations of eclipses of Jupiter's moon, Io. The period of the orbits of Jupiter's moons had previously been perceived to vary, but Roemer pointed out that it is the Earth's movement plus light's constant speed which create this appearance, that is, what we would call a 'Doppler effect.'

In 1677, Guillaume Lamy, in Explication mécanique et physique des fonctions de l'âme sensitive, used the words soul and animal spirits without differentiation: "J'ay pris indifféremment les mots d'âme et d'esprits, ce qui ne doit point faire de confusion, car c'est la mesme chose"(Lamy 1677:176). [added 02/01/03]

In 1678, Huygens, in a communication to the Academie des Science, propounded a wave theory of light propagated through 'aether,' and held that every point on a wave is itself a source of new waves.  At the same time, he reported his discovery of the double refraction of light when viewed in calcite.  This theory was published in 1690 as Traité de la lumière.

In 1678, Edmond Halley returned from St. Helena where he had added 341 stars to the southern hemisphere catalogue with the aid of a telescope.  After observing a transit of Mercury across the Sun, he recognized the possibility of using Venus's transit of the Sun--known to occur in 1761--for determining the distance of the Sun by measuring solar parallax.

In 1679, Giovanni Alfonso Borelli, in De motu animalium, interpreted the locomotory apparatus of vertebrates from a strictly mechanical point of view.  In a study of disease, he concluded that something entered the body which could be remedied chemically.

In 1679, Denis Papin devised a vessel in which the boiling point of water is raised by an increase in steam pressure.  This demonstrated the influence of atmospheric pressure on boiling points. 

In 1682, John Ray described empirically 18,000 species of plant.

By 1683, Anton van Leeuwenhoek, with microscopes, some of which magnified 270 times, had seen red blood cells, sperm cells, and almost all classes of microorganism known today.  He hypothesized that these were carried in the air, not spontaneously generated.  Also, van Leeuwenhoek was able to faithfully describe the nervous system and was the first to describe the life cycle of an ant, from egg to larva to pupa to adult. [added 02/01/03]

In 1684, Gottfried Wilhelm von Leibniz published his system of calculus, developed independently of Newton.  It is Leibniz's notation which has been adopted.  He also invented a scheme for a logical syntax which he called the 'Universal Characteristic' and which "was supposed to enable us to compute the probabilities of disputed hypotheses relative to the available data" (Hacking 1975:140).

In 1687, Newton published Philosophiae naturalis principia mathematica, a summary of his discoveries in terrestial and celestial mechanics in which he makes continual use of Euclidean theorems and constructions, and the first published account of his calculus.  In contrast to Kepler, he did not explain the features of the solar system by deducing them from a purpose.  In contrast to Descartes, he carefully preserved the distinction between mathematical descriptions and theories about matter and causation.  For example, writing of gravitational attraction, he said that "our purpose is only to trace out the quantity and properties of this force from this phenomena, and to apply what we may discover in some simple cases [e.g., the moon] as principles by which, in a mathematical way, we may estimate the effects thereof in more involved cases [e.g., the planets]"....  Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external, and by another name is called duration (Newton 1729:550).  The first part of the Principia concerns dynamics and includes his laws of motion, the second concerns fluid motion, and the third, the mechanical unity of his principle of gravitational attraction in relation to the 'centripetal force' of the planet's motion, that is, Kepler's laws of planatary motion. "Newtonian mechanics [may be] understood as the combination of two laws: the law of motion, according to which force is equal to mass times acceleration; and the law of universal gravitation, according to which the force of attraction between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance separating them" (Sokal and Bricmont 1998:64).  "In opposition to the pre-Galilean and pre-Cartesian conception, which understood motion as a species of becoming..., the new, or classical, interpretation interprets motion as a kind of being, that is, not as a process, but as a status, a status that is just as permanent...as rest" (Koyré 1965:9). Holding that the Earth's rotation, its motion, is relative to absolute space, Newton finds it necessary to distinguish "time, space, place, and motion...into absolute and relative, true and apparent, mathematical and common.  [E.g.,] absolute space, in its own nature, without relation to anything external, remains always similar and immovable"....  Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external, and by another name is called duration (Newton 1729:6).

At the same time, Newton wished to demonstrate that the world which obeyed these laws was compatible with the sort of atoms which he imagined, atoms which were aethereal forces as everything else.  These forces counted among their number, at a minimum, inertia and gravity, which are proportional to each other, cohesion, or the mutual attraction and repulsion that the particles have for each other, and fermentation, and were, so Newton believed, "capable of holding identical particles in a sufficient variety of patterns to explain all the manifold diversity of Nature" (Thackray 1970:15).  Between the gravitating bodies are particles of a rarified medium, or aether, which are the repelling force.  Similar particles also account for the force which deflects the light through a prism (Cantor and Hodge 1981:1-2).  In addition, these forces were also capable of alchemical transmutation, i.e., "every body can be transformed into a body of another kind, and can take on all the intermediate grades of qualities" (Newton, quoted in Koyre 1965:14).  This, from the first edition, was modified in the 1713 edition and that modified in the 1729 edition, reflecting shifts in Newton's thought.

In other words, there are two trends: The panmathematism of Galileo and Descartes and the empirical, experimental 'corpuscular philosophy' of Gassendi, Roberval, Boyle, and Hooke. "From this perspective...Newton presents us with a synthesis of both trends, of both views" (Ibid.:12). As for Newton's particles vis à vis Huygens' waves, it was not understood until the nineteenth century that these conceptions were not contradictory but complementary.

In 1690, Papin invented a pump with a piston raised by steam. 

In 1690, John Locke, in Essay Concerning Human Understanding, repudiated the traditional notion of innate ideas and described the mind at birth as a tabula rasa, or blank slate, upon which the world describes itself through the experience of the five senses.  He also dealt with the probability of inferences.  In the same year, he published Two Essays on Civil Government, in which he maintained that it is the nature of man to be good, the state is formed by a social contract, and each man has the right to the product of his own labor.

About 1692, Newton wrote De Natura Acidorum in which he set up a hierarchy from irreducible particles to particles of the first and second composition, and claimed that "if the particles of the first, or perhaps of the second composition of gold could be separated, that metal might be made to become fluid, or at least more soft.  And if gold could be brought once to ferment and putrefie, it might turn into any other body whatsoever" (Newton, quoted in Thackray 1970:24).

In 1693, Ray, in Synopsis of Quadripeds and Snakes, disproved Descartes' claim that animals are unconscious.

In 1693, Edmund Halley discovered the formula for the focus of a lens: If o is the distance of the object from the lens, i is the distance of the image, and f is the distance of the focus, then 1/o + 1/i = 1/f.

In 1694, Rudolph Jakob Camerarious, in De Sexu Plantarum Epistola, reported the existence of sex in flowering plants.

In 1698, Thomas Savery patented an engine which produced a vacuum by condensing steam.  It was employed for raising water from a mine and supplying water to several country houses.

In 1704, Newton, in Opticks, presented his discoveries using light and elaborated his theory that it was composed of particles.  These particles, he assumed, were composed of uniform matter and space but of varying density depending on the amount of space between the particles. Writing of Huygens work with calcite where light has 'sides,' Newton found "an analogy between the two sides of the light beam and the two ends of a magnet that constitute its poles [and called] this property polarized light" (Fisher 2001:362).  He also inferred from the cohesion of "homogeneal hard Bodies...that their Particles attract one another by some force which in immediate contact is exceedingly strong" (Newton 1730:388-389).

In 1704, Johann Sebastian Bach began composing music--music which was related to the musical consequences of the Pythagorean-Platonic proportional number systems, i.e., "the creation of the universe according to...the Timaeus, the best exposition of the numerical world-order Bach intended to depict" (Humphreys 1983:30-13).  This was the same year in which Newton, in Opticks, chose to add 'indico' to the spectrum of violet-blue-green-yellow-orange-red because "he wants the colors to correspond to the seven notes of the [Pythagorean] music scale" (Park 1990:264).

In 1705, Halley, in Synopsis of Cometary Astronomy, observed that the comet which had appeared in 1682 was the reappearance of comets which had appeared in 1531 and 1607 and predicted its reappearance in 1758.

In 1708, Hermann Boerhaave, in Institutiones Medicinae, recommended the Hippocratic method of bedside instruction and post-mortem examination where, for example, the relation between lesions and symptoms could be studied. 

In 1709, Gabriel Daniel Fahrenheit constructed an alcohol thermometer and, five years later, a mercury thermometer.

In 1710, Jean Bernoulli pointed out that Newton had not proved Kepler's law of ellipses but only its converse and did so himself using calculus, solving "the general problem by reducing it to the same integral that is used to solve it today" (Park 1990:416).

In 1710, George Berkeley, in Principles of Human Knowledge, attacked Newton's notion of 'absolute space.'  He believed that qualities, not things, are perceived and that perception is relative to the perceiver.

In 1713, Newton, in a new edition of Principia, introduced the electric effluvium or aether as a "subtle, all-pervasive spirit, by whose 'force and action' material particles 'attract one another at near distances..., as well repelling as attracting the neighboring corpuscles' " (Newton, quoted in Heilbron 1979:239).

In 1713, Jakob Bernoulli, in Ars conjectandi, expounded the theorem that, in an increasing number of binary trials, an increasing proportion of the total probability is concentrated in the neighborhood of the original probability of success in a single trial.  Bernoulli's theorem forms today the simplest case of the Laws of Large Numbers.

In 1714, Leibniz, in Monadology, said that the Universe's ultimate constituents are 'monads,' simple substances, each of which perceives the Universe from a different point of view.  Their perceptions are harmonius, and what is needed, he said, is a mathematics which will demonstrate the universality of the relations between these points of view.

[In 1714, the British parliament set up the Board of Longitude, consisting of scientists, naval officers, and government officials, which was "perhaps the world's first research and development agency" (Sobel 1995:54).  The Board was empowered to make financial awards in pursuit of a means to determine longitude at sea.  The two competing methods were astronomical calculation, which meant plotting the position of the moon against known stars, and by chronometer, which meant timing the position against a known land longitude.]

In 1715, Thomas Fairchild produced the first artificial hybrid plant.

In 1715 and 1716, Leibniz corresponded with Samuel Clarke to whom he strongly criticized the philosophy and the theological implications of Newton's work.  "The parts of space are not determined and distinguished, but by the things which are in it;" "instants, considered without things, are nothing at all" (Clarke 1717:78, 27).  In other words, Leibniz sees space and time as orders of coexistent and successive phenomena, not real substances but rather relations.

In 1717, Jean Bernoulli propounded the 'Principle of Virtual Displacements: "Any time there is a state of equilibrium of given forces..., then, the sum of the positive energies will be equal to the sum of the negative energies taken positively" (Bernoulli, quoted in Duhem 1905:432).

In 1718, Louis Joblot demonstrated that the microorganisms observed in solutions were the result of being brought in from the ambient air, which confirmed van Leeuwenhoek's conclusion.

Beginning in 1718, Mary Wortley Montagu publicized the use of inoculation against smallpox in Turkey.

In 1718, Halley said that stars move, i.e., they are not fixed to a single framework, since they had changed position since Ptolemy's Almagest.

In 1718, Abraham de Moivre, in Doctrine of Chances, said chance can neither be defined nor understood, but probabilities could be calculated.

In 1720, Wilhelm Jacob van 'sGravesande began the publication of the first modern survey of physics, Physices elementa mathimatica experimentis confirmata, sive introductio ad philosophiam newtonianam, in which he took physics to be a branch of mathematics.  Of electricity he said that it is that "Property of Bodies by which they attract, and repel lighter Bodies at a sensible distance" ('sGravesande, quoted in Heilbron 1979:241).

In 1725, John Flamsteed completed the Historia coelestis Brittannica, a star catalogue far more accurate than its predecessors.

In 1725, Giovanni Battista Vico, in Principi di Scienza Nuova, maintained that history is a man-made account of societies and their institutions.

In 1727, George Graham and Anders Celcius, independently, determined that a disturbance on the sun was a magnetic storm.

In 1727, Stephen Hales studied the ascent of water in plants and applied physical principles to the study of plant physiology.

In 1728, Pierre Fauchard, in The Surgeon Dentist, described preventive measures to keep teeth healthy as well as inventing the word 'dentist.'

In 1729, Stephen Gray discovered electrical induction, which he called 'communication,' and announced it in 1732.  He also distinquished between conductors and insulators (Heilbron 1979:245-249).

In 1729, James Bradley announced his discovery of the aberration of starlight, which is occasioned through the joint effect of the Earth's motion and the non-instantaneous transmission of light.  His efforts to gauge the distance to the stars provided the first concrete evidence that the Earth moves through space and also the true value of the speed of light, improving on Roemer's estimate.

In 1730, George Brandt discovered cobalt.

In 1730, Charles François de Cisternay Dufay found that "almost everything except metals and very hard gems could be made phosphorescent" (Heilbron 1979:251).

In 1731, John Hadley and, independently, Thomas Godfrey built reflecting quadrants by which the elevation of two celestial bodies and the distance between them could be measured at sea.  This instrument, by adding a telescope and a wider measuring arc, quickly evolved into the sextant.

In 1733, Hales measured blood pressure.

In 1733, Chester More Hall built an achromatic compound lens using glasses with different refractive indexes.

Beginning in 1733, Dufay, in Mémoires sur l'électricité, summarized and generalized what was known about electricity: E.g., that all materials, except metals and those too soft to rub, can acquire electricity and all materials, especially metals, can "display the virtue after contact with an excited electric" (Heilbron 1979:252).  This latter principle became known as 'Dufay's rule.' ' He made discoveries, e.g., "objects with dissimilar electrifications attract, those with like electrifications repel," but his explanations were transient (ibid.:254-260).

In 1733, John Kay patented the flying shuttle loom. [added 02/01/03]

In 1734, David Hume, in A Treatise on Human Understanding, described the mind as a bundle of perceptions, causal relation as the conjunction of two events, and and apparent sequence of events as, in fact, a sequence of perceptions.  Thus the connections which science establishes are "entirely arbitrary," and the "utmost effort of human reason is to reduce the principles, productive of natural phenomena, to a greater simplicity" (Hume 1738:30).

In 1736, Leonhard Euler, in Mechanica, solved the Königsberg Bridge Problem, that is, whether it were possible to perambulate the seven bridges of Königsberg without retracing one's steps.  He did so by means of the first graph theoretic model ever published.  His theorem is this: To be traversable every pair of points, or in this case land areas, can reach each other, and the number of lines, or bridges, is even.

In 1736, John Harrison finished building and tested at sea what proved to be the first accurate chronometer for timing longitude.

[By 1737, fifty years after the publication of Newton's Principia mathematica, the opposition to Newtonism had crumbled away.  "The uncommon incomprehensibility became a common incomprehensibility," as Ernst Mach expressed it (Mach, quoted in Koyré 1965:17).  The real world is no longer "conceived as a finite and hierarchically ordered...whole, but as an open, indefinite, and even infinite universe, united not in its immanent structure but only by the identity of its fundamental contents and laws...; a universe in which...astronomy and physics became interdependent and united because of their common subjection to geometry.  This, in turn, implies the disappearance...from scientific thought of all considerations based on value, perfection, harmony, meaning, and aim" (ibid.:7).  "The Newtonian law of attraction...is not only the only law of that kind that explains the facts but, besides, is the only one that can be uniformly and universally applied to large and small bodies, to apples and to the moon.  It is the only one, therefore, that it was reasonable for God to have adopted as a law of creation" (ibid.:15).  "If order and harmony so obviously prevailed in the world of nature, why was it that, as obviously, they were lacking in the world of man?  The answer seemed clear: disorder and disharmony were man-made....  The remedy seemed clear too: let us go back to nature, to our own nature, and live and act according to its laws....  So strong was the belief in 'nature,' so overwhelming the prestige of the Newtonian (or pseudo-Newtonian) pattern of order arising automatically from interaction of isolated and self-contained atoms, that nobody dared to doubt that order and harmony would in some way be produced by human atoms acting according to their nature, whatever that might be--instinct for play and pleasure (Diderot) or pursuit of selfish gain (A. Smith)" (ibid.:22).]

In 1738, Daniel Bernoulli, in Hydrodynamica, asserted the principle that as the speed of a moving fluid increases, the pressure within the fluid decreases.In the process of determining this, he invented the 'molecular theory of gases,' now known as the 'kinetic theory of gases,' which introduced the notion that the gas particles were moving around rapidly, colliding and rebounding according to the laws of elementary mechanics; i.e., a gas's temperature is a function of the average speed of its particles.

In 1738, François Marie Arouet de Voltaire, in Éléments de la philosophy de Newton, contributed to the popularization of science and Newton's views.

In 1742, Jean Le Rond D'Alembert introduced the principle which permitted the reduction of a problem in dynamics to one in statics: Kinetic equilibrium is obtained by inventing a fictional force equal in magnitude to the body in question and opposite in acceleration.  This showed that Newton's Third law of motion applies also to bodies free to move.

In 1742, Pierre Louis Moreau de Maupertius, in Discours sur la Figure des Astres, observed that the nebulous stars, or 'nebulae,' "present the figure of ellipses more or less open" (Maupertius, quoted in Kant 1755:50).

In 1742, Jean Bernoulli, in Opera omnia, proved that the orbits of objects bound by the inverse square force are conic sections.

In 1742, Celcius developed the centigrade temperature scale which carries his name.

In 1744, Guillaume François Rouelle described his neutral saline theory, namely, that salt consisted of a generic component, a chrystalline acid, and a specific component, or whatever substance served to coagulate the acid into a solid.
In 1744, Georges Louis Leclerc de Buffon announced that the earth had developed for at least 75,000 years.
In 1744, a 1679 letter from Newton to Boyle was published which described aether in terms of the resistence of the air pushed aside when two glass panes were pushed together and which once together were held thus by the surrounding aether.  British electricians took this to be the latest word on electrical attraction and repulsion (Heilbron 1979:69).

In 1745, Maupertius, in Venus Physique, proposed the notion of descent from a common ancestor. He also proposed that particles from all parts of the body were gathered in the gonads.

In 1745, Charles Bonnet demonstrated the regenerative ability of annelid worms.

In 1746, Bonnet discovered that aphids are parthenogenic.

In 1746, Étienne Bonnet de Condillac, in Essai sur l'origine des connaissances humaines, developed the theory that all knowledge comes from the senses and there are no innate ideas.

In 1746, Andreas Cunaeus invented the 'Leyden jar,' a form of capacitor.  It consists of "a glass jar with a layer of metal foil on the outside and a similar layer on the inside.  Contact to the inner foil is by means of a loose chain hanging inside the jar" (Dictionary of Physics 2000:264).  This contraption created a small current which shocked experimenters who quickly demonstrated that a circuit could be extended to hundreds of people (Heilbron 1979:312-318).

In 1747, Julien de la Mettrie argued, in L'Homme Machine, that thought was a property of organized matter.

In 1747, Bernard Siegfried Albinus, with the engraver Jan Wandelaar, published Tabulae Sceleti et Musculorum Corporis Humani, a series of illustrations of the human skeleton and successive muscle layers.

In 1747, Maupertius showed that the impact of a collision between two objects can be analyzed by the 'principle of least action,' in which the path of the motion will follow that which minimizes the action.

In 1748, Bradley announced that there were tiny deviations in the Earth's axis caused by the pull of the Moon.

In 1749, Buffon began the publication of the 44 volumes of Histoire Naturelle, in which he drew attention to vestigial organs and asserted that species are mutable.

In 1750, Thomas Wright, in An Original Theory or New Hypothesis of the Universe, described the Via Lactea, or Milky Way, as a disc, saying we must imagine the stars "all moving the same Way, and not much deviating from the same Plane, as the Planets in their heliocentric Motion do around the solar body" (Wright 1750:137).  Saying that "we have no reason to suppose that the nature of our Sun is different from the rest of the Stars," he took it that there was a great "Multiplicity of Worlds" (ibid.:131).  He also took the 'cloudy stars' to be 'nebulae,' or "an infinite Number of small Stars" (ibid.:101) and speculated that some of these 'spherical' galaxies "may be external Creation," that is, outside the Milky Way, which was at that time considered to be coextensive with the Universe (ibid.:177-178).

In 1750, Euler, in "Découverte d'un nouveau principe de mécanique," introduced a notation which gives a name and address to every possible point: "Pour trouver le vrai lieu du corps par rapport à chaque instant, on n'aura qu'à le rapporter en même tems à trois plans fixes, qui soient perpendiculaires entr'eux" (Euler 1750:89) (To find the true place of the body at each instant, one only needs to locate it at the same time in respect to the three fixed planes, each perpendicular to the others).

In 1751, Maupertius, in Système de la Nature, put forward a theory of pangenesis, in which an embryo contained particles derived from all parts of the parent, and heritable novelties arose from changes in fluids or were induced by the environment.

In 1751, Axel Fredric Cronstedt discovered nickel.

In 1751, Benjamin Franklin published Experiments and Observations on Electricity after several years of experiments done with several friends.  In this book Franklin suggested an experiment to prove that lightning is a large-scale electrical discharge, a task which later he took upon himself, using a kite.  This led to the invention of the lightning rod.  In Franklin's theory of electricity, "positively electrified bodies repel one another via short-range forces between the particles of their respective atmospheres."  Such an 'atmosphere,' or "aura of electrical matter" is a once the 'charge,' an aether, and the source of the 'electric field' (Heilbron 1981:190), and flowed from the more highly charged body to the less highly charged, on analogy to hydrodynamical principles (Cantor and Hodge 1981:30).  He invented many the terms which are still used: positive, negative, conductor, battery, etc.

In 1752, René Antoine Ferchault de Réaumur showed by experiment that gastric juice liquifies meat.

In 1752, James Lind called attention to the value of fresh fruit in the prevention of scurvy.

In 1752, Thomas Melvill noticed that "the spectra of flames into which metals or salts have been introduced show bright lines characteristic of what has been introduced" (History of Optics 2001:3).

In 1752, Euler published the proof of the equation relating the number of faces, edges, and vertices of a polyhedron, f+v=e+2.

In 1753, Carl Linné, better known as Carolus Linneas, published Species plantarum, in which he distinguished plants in terms of genera and species.

In 1753, Albinus and Wandelaar published Tabulae Ossium Humanorum, an anatomical study of bones.

In 1753, Euler, in Theoria motus lunae, attempted to solve by analytic function the motions of three interacting bodies, and, though that is not possible by those means, he succeeded in reducing "the relative movements of the Sun, the Earth, and the Moon to a series of elegant equations" (Sobel 1995:970).

In 1754, Joseph Black heated calcium carbonate which separated into calcium oxide and carbon dioide and then recombined back into calcium carbonate.  He called carbon dioxide 'fixed air' because it could be fixed into solid matter.

In 1754, Nicolas Louis de Lacaille returned from the Cape of Good Hope where in a four year period he made nearly two thousand additions to the star catalogue.

In 1754, D'Alembert, in the Encyclopédia article "Différentiel," said that the term 'infinitesimal' meant, not infinitely small, but indefinitely small: "A quantity is something or it is nothing."  He called one quantity the limit of another if the difference is absolutely unaccountable.  "The ratio of the first of these quantities to the second is always much smaller than the second quantity as is the latter than a given quantity" (D'Alembert, quoted in Boyer 1949:249).  This test for convergence is known as 'D'Alembert's ratio.'

In 1755, Maupertius, in Essai de Cosmologie, wrote, "In the fortuitous combinations of the productions of Nature..., only those with certain adaptive relationships could survive....  In the other, infinitely greater part, there was neither adaption nor order.  All these have perished...and the species we see today are only the smallest part of those which a blind destiny produced" (Maupertius, quoted in Hardy 1965:53).
In the 1755, Buffon, in a new edition of Histoire naturalle, suggested that species were directly subject to moulding by their environment, and that these changes were perpetuated by heredity.
In 1755, Immanuel Kant, in Allgemeine Naturgeschichte und Theorie des Himmels, said that "the chaos begins to take form at the points where the more strongly attracting particles are [and fashions] itself by a natural evolution" into stars and planetary systems (Kant 1755:62), conjectured "that new planets will perhaps yet be discovered beyond Saturn" (ibid.:55), and asserted his belief that "most of the planets are certainly inhabited and those that are not, will be at one time" (ibid.:xx), in other words, that if life is supportable, it will occur.  Kant is reputed to have been the first to describe nebulae as 'island universes.'

In 1755, Johann Tobias Mayer, grasping "an advance that applied directly to the longitude problem..., created the first set of lunar tables for the Moon's location at twelve-hour intervals" (Sobel 1995:97).

In 1756, Franz Ulrich Theodosius Aepinus, while studying the electrical properties of a 'Tourmaline crystal,' was struck by its analogy to a magnetized piece of iron and realized that "the causes of magnetic and electrical phenomena were extremely similar" (Aepinus 1759:238).  This led him to generalize the principle of the Leyden jar to include any 'capacitator,' two conducting plate separated by an insulator.  That "made it impossible to maintain the theory of literal atmospheres [and necessitated the admission] that similarly charged bodies repell and dissimilarly charged bodies attract one another" (Heilbron 1979:388).
In 1757, Black discovered latent heat, i.e., he distinguished between heat and temperature.
In 1757, Harrison completed his third timekeeper.  The numerous innovations include a bi-metallic strip which compensates for temperature change and caged ball-bearings to eliminate friction.
In 1758, Linné published the 10th edition of Systema Naturae, where he applied the genera and species system to animals based on their external appearance.
In 1758, Ruggero Giuseppe Boscovich (or Rudjer Boskovic), in Philosophiae naturalis theoria: redacta ad unicam legam virium in natura existentium, claimed that "the particle...is not a thing at all but only a force.  All its actions are actions at a distance, repulsive at short distances and attractive at long ones" (Park 1990:201). "The force varies in a continuous fashion from attractive to repulsive and back to attractive.  The number of such variations can be multiplied at will to account for phenomena.  [Combinations of the centers of force, or points or atoms, yield] the chemical elements, combinations of elements [yield] the chemical compounds, and so on.  Ultimately, then, all 'matter' is one; observable complexities [are] the result of successive levels of complexity of particulate arrangements" (L. Williams 1976:529).  By defining "force solely in terms of a mathematical function describing the change of motion," Boscovich had no intention of examining "the ultimate nature of force" (Cao 1997:26), the truth being unattainable according to his Lockean natural philosophy.

In 1758, Alexis Claude Clairaut conjectured that Halley's comet might be subject to unknown forces, such as another comet or unknown planet.

In 1759, Caspar Friedrich Wolfe examined the developmental anatomy of chick embryos and observed that the different organic systems were formed successively; in other words, that specialized organs develop out of unspecified tissue.
In 1759, Mikhail Vasilevich Lomonsov said the earth's topography was the result of very slow natural activity, including uplift and erosion.
In 1759, Aepinus, in Tentamen theoriae electricitatis et magnetismi, says that the forces exerted by electricity "repel each other mutually even over rather large distances," but he does "not approve the doctrine which affirms the possibility of action in distans....  [He does] not consider either the repulsive force discovered here, or the attractive force called universal gravity, to be forces inherent in matter [but rather] each force arises from some extrinsic cause" (Aepinus 1759:241,240,259).  When he uses the words vortex and atmosphere, he says he is only denoting "the sphere of activity" (Ibid.:392).  He designed the requisite theory-laden experiments to prove that "induction played an important role in even this simplest of all electrical phenomena" (Home 1979:121).  Probably under Euler's influence, he introduced algebra to the study of electricity.  Few of Aepinus' ideas penetrated the thoughts of most electricians before the late 1770s and by then, it was considered, and is still considered, that he fathered the action-at-a-distance/localization of charge theory of electricity and magnetism.

In 1759, the return of Halley's comet confirmed Newton's mechanics.

In 1761, Giovanni Battista Morgagni published a book which recommended studying body's organs rather than its parts, and proposed that the symptoms of disease resulted from pathological changes in the organs.

In 1761, Johann Heinrich Lambert, in Cosmologische Briefe über die Einrichtung des Weltbaues, arrived, independently of both T. Wright and Kant, at the idea that we live in an ordinary galaxy.

Between 1761 and 1766, Joseph Gottlieb Kölreuter published accounts of 136 experiments in artificial hybridization and drew the conclusion that inheritance was quantitative.

In 1761, Euler, in Lettres à une Princesse d'Allemagne, writing of the aether-filled pores in a lodestone, said "ces pores sont disposés de manière à avoir communication entre eux, et costituent des tuyaux ou canaux par lesquels la matière magnétique passe d'un bout à l'autre" (Euler 1789:453).  [These pores are disposed in a manner to have communication between them, and constitute tubes or canals through which the magnetic material passes from one end to the other.]

In 1762, Marcus Antonius Plenciz, in Opera medico-physica, said that living agents were the cause of infectious diseases.

In 1762, Johan Carl Wilke designed a dissectible condenser, a precursor of the 'electrophorus,' or electrostatic generator, a device to build up an electric charge.  Explaining his theory, he distinquished "between the communication of electrical matter and the segregation of the normal supply of one body by the action of the atmosphere of another" (Heilbron 1979:419).

In 1763, Thomas Bayes, in an essay on the doctrine of chances, attempted to establish the rule that the probability of an event in no way depends on any prior observations.

In 1764, James Hargreaves invented the spinning jenny.  [added 02/01/03]

In 1765, Lazzaro Spallanzani reconfirmed Joblot's results and extended them, establishing that microbes are never spontaneously generated.  Nonetheless, spontaneous generation continued to find adherents until Louis Pasteur's 1862 paper.

In 1766, Nevil Maskelyne, in the Nautical Almanac and Astronomical Ephemeris, introduced the determination of longitude by lunar distances and calculated these annually until he died in 1811.

In 1766, Johann Daniel Titius said that if one took "the Earth's distance from the Sun as 10, the mean radial distances of the planets [are] almost exactly proportional to the terms of the expression 4 + 3 (2n)" (Grosser 1979:27).  In 1772, Johann Elert Bode began publicizing Titius' insight to the extent that it became known as Bode' law (though it is not, being neither invariant nor universal).

In 1766, Henry Cavendish isolated and described 'inflammable air,' later named hydrogen by Antoine Laurent Lavoisier, and distinguished it from carbon dioxide.

In 1768, Euler proposed that the wave length of light determines its color.

In 1769, James Watt patented a new type of steam engine with a separate condensing chamber and an air pump to bring steam into the chamber and equipped it with a simple 'governor' for safety: if the engine started to go too fast, the power would be automatically cut back.  He coined the term 'horsepower' and later loaned his name to the unit of power, or work, done per unit of time. 

In 1769, Denis Diderot, in Le Rêve de D'Alembert, dealt with, among other things, animal reproduction, mutation, eugenics, the mechanical system of the body, and the nervous system.

In 1770, Lambert, in Vorlóufige Kenntnisse für die, so die Quadratur und Rectification des Circuls suchen, provided a mathematical proof that the ratio of the circumference of a circle to its diameter, or p, is an irrational number.

In 1771, Cavendish, in "An Attempt to explain some of the Principle Phaenomena of Electricity by Means of an Elastic Fluid," observed that "a body can be both positively electrified and undercharged or, to use modern terminology, to have a positive potential and a net negative charge" (Heilbron 1979:481).  He dispensed with aether and made do with "localized charge, actions at a distance between elements of the electric fluid, and even repulsions between the particles of common matter" (Ibid.:478).

In 1772, Daniel Rutherford described nitrogen, which he called 'residual air.'

About 1773, Karl Wilhelm Scheele isolated oxygen from silver carbonate, but did not publish his discovery until later than Joseph Priestly.  He also showed that nitrogen was a constituent of air, and isolated glycerol and numerous acids including tartaric, lactic, uric, prussic, citric, malic, and gallic.

After 1773[?], Otto Frederik Müller distinguished two types of bacteria, bacillum and spirillum.

Between  1773 and 1776, James Burnett Monboddo published a three-part work, On the Origin and Progress of Language, that argued for an evolutionary view of human origins, and contemplated educating orang-outangs.

In 1773, David Bushnell designed and built the first submarine, the Turtle, a diving-bell-like craft, which seated one-man who propelled it with a hand-crank. [added 02/01/03]

Before 1774, Priestly discovered sulphur dioxide, ammonia, and 'dephlogisticated air,' later named oxygen by Lavoisier.

In 1774, Franz Anton Mesmer began the psychotherapeutic practive of hypnotism, which he called 'animal magnetism' and conceived it to be an actual fluid.  Apparently he had some success with psychosomatic illnesses.  Part of his technique seems to have been used earlier by exorcists.

In 1774, Lavoisier recognized that the gas 'fixed air,' or carbon dioxide, was a chemical and produced it by combining oxygen with carbon obtained from charred vegetables.  In subsequent papers, the main idea was that combustion processes, including vegetative metabolism and fermentation, took place by the decomposition of water which supplied the oxygen.  The addition of oxygen to the organic substances accounted for their weight increase.

Beginning in 1774, Pierre Simon Laplace, with "Mémoire sur la probabilité des causes par les événements," set out to establish 'probability' as the mathematical basis "for statistical inference, philosophic causality, estimation of scientific error, and quantification of the credibility of evidence, to use terms not then coined" (Gillispie 1976:280).  Forty years later, he wrote Essai philosophique sur les probabilités to serve as an introduction to the second edition of Théorie analytique des probabilités, both intended to be read by laymen.

In 1775, Johann Friedrich Blumenbach published De generis humani varietate nativa, which marked the beginnings of physical anthropology.

In 1775, Alessandro Volta invented the 'electrophorus' and Wilcke explained the theory of its operation.

In 1775, John Landen, in an article in the Philosophical Transactions of the Royal Society, demonstrated that "every arc of a hyperbola can be measured by two arcs of an ellipse....  The term 'Landen's theorem' was applied not only to this result but also to the first known transformation of elliptic integrals" (Itard 1976:139).

In 1776, Cavendish, in "Some Attempts to imitate the Effects of the Torpedo [an electric eel] by Electricity," demonstrated that "by multiplying the number of [a battery's] elements one can preserve the stroke while decreasing the electrification" (Heilbron 1979:489).  This was a continuation of his research into the comparative 'resistance' of solutions, never published, where he "established that fresh water resisted 100 times better than salt" (Ibid.:487).

In 1776, Adam Smith, in The Wealth of Nations, advanced the idea that businesses survive through successful trading in pursuit of their self-interest, and that the resulting equilibrium was not by design.

In 1778, Joseph de Herbert, in Theoriae phenomenorum electricorum, wrote, "Electrical actions do not originate in the transition of fluid from a body with a surplus to one deficient, but...by action at a distance" (Heilbron 1979:425).

In 1779, Jan Ingelhousz showed that plants use carbon dioxide and that they require light in order to produce oxygen.

In 1780, Spallanzani demonstrated that contact between the sperm and egg is necessary for fertilization.

In 1780, Lavoisier and Laplace developed a theory of chemical and thermal phenomena based on the assumption that heat is a substance, which they called 'caloric' and deduced the notion of 'specific heat,' which they expressed in terms of the heat absorbed in raising one pound of water one degree.  They also concluded that respiration is a form of combustion.

In 1781, Cavendish synthesized water by exploding hydrogen in oxygen.

In 1781, Frederick William Herschel discovered the planet Uranus by its movement, although at the time he supposed it to be a comet.  Later the same year, Anders Johann Lexell concluded that it was a planet.  The radius predicted by Bode's law agreed within two percent of the observed radius.  Earlier, it had many times in various locations been identified as a star.

In 1781 and 1787, Kant, in Kritik der reinen Vernunft (Critique of Pure Reason), said that reason's function is to synthesize sense data, a process in which the mind relies on certain intuitive principles, such as causality, which, since they cannot be induced from sense data, "must be 'a priori,' i.e., logically prior to the materials which they relate....  These formal elements [are] 'transcendental'....  They transcend or are distinct from the sensuous material" (Dictionary of Philosophy 1984:175).  In other words, Kant turned the object of philosophy from modes of being, or ontology, to ways of knowing, or epistomology, and space and time into forms for the intuitive representation of objects.

In 1782, Peter Jacob Hjelm discovered molybdenum.

In 1783, Spallanzani said that digestion is not merely chewing but is a chemical process.

In 1783, Lazare Nicolas Marguerite Carnot, in Essai sur les Machines en Général, specified the optimal and abstract conditions for the operation for all sorts of actual machines.  In this subject it was "the first truly theoretical treatise.  A machine is an intermediary body serving to transmit motion between two or more primary bodies that do not act on one another....  Wishing to attribute to machines no properties except those common to all parts of matter, Carnot envisaged them as intrinsically nothing more than systems composed of corpuscles [in which] the net effect of mutual interaction among the corpuscles constituting the system is zero" (Gillispie 1976:72,73).  He also introduced the idea of 'geometric motion,' or 'displacement,' what in later mechanics was called 'virtual displacement.'

In 1783, John Michell pointed out that a star that was sufficiently massive and compact would have such a strong gravitational field that light could not escape.

In 1783, Joseph Michel Montgolfier and Jacques Étienne Montgolfier invented the first practical hot air balloon.  Later the same year, Jacques Alexandre César Charles became the first person to ascend in a hydrogen balloon, for which he "invented the valve line (to enable the aeronaut to release gas at will for descent), the appendix (an open tube through which expanded gas could escape, thus preventing rupture of the balloon sack), and the nacelle (a wicker basket suspended by a network of ropes covering the balloon and held in place by a wooden hoop)" (Gough 1976:208).

In 1784, John Goodricke identified Delta Cephei as a variable star.

In 1785, Laplace, in Théorie des attractions des sphéroides et la figure des planètes, reformulated the theory of gravitating bodies, building it around a function V, the "integral of the quotients of the gravitational mass dm [divided] by their respective distances from the point P at which V is to be computed....  The function V simplified the calculations...by allowing work with a scalar, additive quantity, rather than with force" (Heilbron 1979:498).  Laplace also encouraged his theory's application to electricity.
In 1785, Charles Augustin de Coulomb, in "Oú l'on détermine suivant quelles lois le fluide magnétique ainsi que le fluide électrique agissent," said that "the reciprocal attraction of the electrical fluid called positive, on the electrical fluid ordinarily called negative, is in the inverse proportion of the squares of the distances" (Coulomb, quoted in Heilbron 1979:473).
In 1785, Adrien-Marie Legendre, in "Recherches sur la figure des planètes," made "an account of the law of reciprocity of quadratic residues and [stated] a theorem which later became famous: Every arithmetical progression whose first term and ratio are relatively prime contains an infinite number of prime numbers" (Itard 1976:135).
In 1786 and 1787, Coulomb, in "Oú l'on démontre deux principles propriété du fluide électrique" and "Sur la manière dont le fluide électrique se partage entre deux corps conducteurs mis en contact," said that the electrostatic force between two charged bodies is proportional to the product of the amounts of charge on the bodies divided by the square of the distance between them.  "He represented the distribution as the varying density of one or the other electrical fluid," which density he arrived at by using torsion beams, 'proof planes,' and accounting for leakage (Heilbron 1979:494-495).
In 1786, Kant, in Metaphysische Anfangsgründe der Naturwissenschaft (Metaphysical Foundations of Natural Science), suggested the doctrine of the unity and convertibility of forces.

In 1786, Franklin, in Maritime Observations, published a chart of the Gulf Stream.

In 1787, Charles determined by experiment that "the volume of a fixed mass of gas at constant pressure is proportional to its thermodynamic temperature" (Dictionary of Physics 2000:70).  This was published by Joseph Louis Gay-Lussac in 1802.

In 1787, Herschel discovered the two largest satellites of Uranus and, two years later, the Saturnian satellites Mimas and Enceladus.  His observations of double stars established that many are in orbit around each other.

In 1788, Jean Senebier demonstrated that it is light, not heat, from the sun that is effective in photosynthesis.

In 1788, Joseph Louis Lagrange, in Mécanique analytique, developed that part of mechanics which deals with particles and rigid bodies using procedures general enough that they were, and still are, applicable to all calculations. Newton's "dynamical theory contains truth but not method. Lagrange's Mécanique is a method. First, one looks to see whether the system under analysis has a symmetry of some kind....  Corresponding to any symmetry there is some dynamical quantity that remains constant."  Thus, often the solution to an equation "follows at once from the existence of the symmetry," which is called a 'Lagrangian' (Park 1990:248-249).  This work is presented solely by algebra and calculus, with no diagrams and no geometry.

In 1789, Antoine Laurent de Jussieu, in Genera Plantarium, stressed the significance of the internal organization of organisms.

In 1789, Lavoisier proved that mass is conserved in chemical reactions and created the first list of chemical elements.  This classification is the basis of the modern distinction between elements and compounds.  He also demonstrated that glucose itself could be fermented and was made up of ethanol and carbon dioxide.

In 1789, Jean Baptiste Joseph Fourier, in a paper submitted to the Académie des sciences, explicated his discovery of a new proof of Descartes' rule of signs, f (x).  "The details of the proof may be seen in any textbook dealing with the rule, for Fourier's youthful achievement quickly became the standard proof" (Ravetz and Grattan-Guinness 1976:99).

In 1789, Jeremy Bentham reoriented semantics "whereby the primary vehicle of meaning came to be seen no longer in the term but in the statement, [that is,] as the unit accountable in the empiricist critique" (Quine 1953:39,42).

In 1790, Kant, in Kritik der Urtheilskraft, said that the analogy of animal forms implied a common original type and thus a common parent.
In 1790, Johann Wolfgang von Goethe, in Metamorphose de Pflanzen, sought to discover the 'primal plant,' and coined 'morphology.'
In 1791, Franz Joseph Gall, in Untersuchungen über Natur und Kunst im kranken und gesunden Zustande des Mensch, described the nervous system as a series of separate but interrelated ganglia. "The inclusion of the cerebral cortex in this scheme was an important development away from lingering glandular and humoral conceptions" (R. M. Young 1978). [added 02/01/03]
In 1791, Luigi Galvani, in De viribus electricitatis in motu musculari, showed that it was possible to control the motor nerves of frogs using electrical currents, i.e., that the nerves transmitted electricity.  He used a measuring instrument of his own invention involving a wire coil around an iron core between the poles of a magnet.  The movement of the sides of the coil when a current passes through it causes a measurable deflection of a light beam.  This became known as a 'galvanometer.'

In 1791, Goethe published "Zur Optik," which led, in 1810, to the publication of Farbenlehre, a compendium of chromatic phenomena.  He sought a personalized relation to a holistic continuity of inorganic and organic nature which he opposed to Newtonian reductionism's dependence on theoretical constructs.

In 1791, Pierre Prévost proposed the theory that when a body is not at the same temperature as its surroundings, heat will flow between them.

In 1792, Volta discovered he could arrange metals in a series in such a way that chemical energy is converted into electrical energy; that is, two dissimilar metals are submerged in an electrolyte and connected by an circuit and thereby exchange electrons.  By 1800, he had invented the so-called voltaic cell, a pile of such metals "consisting of pairs of silver and zinc disks separated by pieces of moist cardboard" (Heilbron 1979:493-494).

In 1792, Jeremias Benjamin Richter published his measurements of 'equivalent weight,' that is, how much of a given acid is required to neutralize a given base.

In 1792, T. Wedgwood noticed that various materials, when heated, all turn red at the same temperature.

In 1794, Erasmus Darwin, Charles' grandfather, proposed that "warm-blooded animals have arisen from one living filament...possessing the faculty of continuing to improve by its own inherent activity, and of delivering those improvements by generation to its posterity."  He also suggested that the conflict between males over which "should propagate the species" had the final cause that the species "become improved" (E. Darwin 1794:505,503).

In 1794, Eli Whitney patented the cotton gin. [added 02/01/03]

In 1795, James Hutton, a proponent of the vast antiquity of geological formations, wrote Theory of the Earth, the earliest comprehensive treatise which can be considered a geologic synthesis.  Confining his attention to the earth's dynamics, he deplored speculative attempts to account for the origin of processes which could be observed in current operation.  James Hall succeeded in devising experiments which reproduced in miniature the processes which, according to Hutton, are responsible for the formation of rock strata under the conditions prevailing in the earth's crust.

In 1796, Edward Jenner investigated the folk tale that milk maids were immune to small pox, the virus variola major, and in a brief series of experiments confirmed that exposure to cow pox, the virus vaccinia, rendered immunity.  The principle that a survivor of a disease such as smallpox or the plague was usually able to resist a second infection had long been observed.  By the late eighteenth century, vaccination was understood and employed in Turkey for smallpox.  The method involved the inoculation of children on the skin with 'matter' from the pustule of a mild case.  In most instances, the child showed mild symptoms and was subsequently immune.
In 1796, Lagrange called dynamics a four-dimensional geometry.
In 1796, Laplace, in Exposition du système du monde, hypothesized that the solar system was created from a spinning cloud of gas.  "Gravity pulled most of the gas to the center, thereby creating the sun.  At the same time, some of the material, because of its spin, could not be absorbed by the young sun and instead settled into a disk.  Eventually these dregs became the planets" (Ray 2000:43). In the nineteenth century, this theory of the origins of the solar system was known as the Kant-Laplace theory.
In 1796, Carl Friedrich Gauss discovered that the regular heptagon was inscribable in a circle, using only a compass and a straightedge--the first discovery in Euclidian construction in over 2000 years.
In 1797, Frederick Wilhelm Joseph von Schelling, in Ideen zu einer Philosophie der Natur, said that, while the difference between the forces of mind and nature must be only a matter of degree, nature is subordinate to mind and that knowledge is absorbed in the unity of mind and matter.

In 1798, Thomas Robert Malthus, in his Essay on the Principle of Population, contended that population increses by a geometric ratio whereas the means of subsistence increase by an arithmetic ratio.

In 1798, Cavendish constructed a torsion balance by which he measured the mean density of the Earth. 

In 1799, Joseph Louis Proust ennunciated the 'Law of definite proportions,' which he had arrived at by showing that copper carbonate contained definite proportions of copper, carbon, and oxygen, independent of the method of preparation.

In 1799, Humphrey Davy, in "An Essay on Heat, Light, and the Combinations of Light," hypothesized that heat was not caloric, as Lavoisier had asserted, but was 'motion,' as Newton had asserted.

In 1799, Laplace began the publication of Traité de mécanique céleste, "an encyclopedia of calculations relating to the six known planets and their satellites, to the shapes of the rotating planets, and to the tides in the earth's oceans" (Park 1990:252). Systéme du monde served as an outline for this larger work.

In the beginning of the nineteenth century, Franz Joseph Gall speculated that the cerebral cortex represented the highest level of the brain and that its development characterized mammals.  His aim was to localize cerebral functions by introspection, i.e., phrenology, and theorized that abstract mental functions, such as secrecy or mother love, occur in discrete areas of the cerebral cortex.  He further believed that each mental function, that is, each bump on the cortex, would grow through use, on analogy to muscles.
In 1800, Marie François Xavier Bichat published the first of several books dealing with the pathology of tissues.

In 1800, Karl Friedrich Burdach introduced the term 'biology,' which replaced 'natural history,' which traditionally had three components, zoology, botany, and mineralogy.
Beginning in 1800, Gall, with the assistance of Johann C. Spurzheim, discovered the origins of the first eight cranial nerves, traced the fibers of the medulla oblongata to the basal ganglia, and, in the cerebral cortex, established the contralateral decussation of the pyramids. [added 02/01/03]

In 1800, William Nicholson and Anthony Carlisle showed that chemical reactions could be produced by electricity by decomposing water into hydrogen and oxygen in a process which came to be known as 'electrolysis.'
In 1800, Herschel, noting a temperature rise on a thermometer placed beyond the visible red light cast by a prism, hypothesized the existence of infrared and of radiant heat.

In 1801, John Dalton, in "New Theory of the Constitution of Mixed Aeriform Fluids, and Particularly of the the Atmosphere" and three supplementary papers, formulated, independently of Charles, the law of gaseous expansion at constant pressure and the law of gaseous partial pressures which stated that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressure of the individual gases; i.e., "when two elastic fluids, denoted by A and B, are mixed together, there is no mutual repulsion amongst their particles; that is, the particles of A do not repel those of B, as they do one another.  Consequently, the pressure or whole weight upon any one particle arises solely from those of its own kind" (Dalton, quoted in Thackray 1976:541).  Thus did Dalton dismiss the Newtonian gospel of chemical affinity as a force in the atmosphere.

Later in 1801, William Henry found that "at a given temperature the mass of gas absorbed by a given volume of water is directly proportional to the pressure of the gas" (Thackray 1976:541).  This is known as Henry's law.

In 1801, Thomas Young, in "On the theory of light and colors," proposed that light striking the retina creates vibrations and the frequency of the vibrations excites a particular nerve filament, "one for each principle colour" (Young 1802:20).  He also made the observation that if light from a single source is split into two beams, then recombined and projected on a screen, dark and light fringes appear.  This he interpreted as wave motion: The dark fringes occur when the crest of one beam coincides with a trough of the other. At that time, Newton's particle theory was thought by most physicists to exclude the possibility of light moving in waves. As the transmission medium Young proposed the undulatory motions of aether which he supposed to be an elastic fluid (Cao 1997:28).  Aether, according to a contemporary source, "being no object of our sense, but the mere work of imagination, brought only on the stage for the sake of hypothesis, [so] authors take the liberty to modify it as they please" (Encyclopedia Britannica, 1797, quoted in Heibron 1981:187).

In 1801, William Hyde Wollaston established the equivalence of galvanic and frictional electricity.

In 1801, John Robison, in a treatise in the Encyclopedia Brittanica, explained electrostatic theory, citing the theories of Aepinus and Coulomb.  About 1770, Robison had devised an apparatus for measuring the force of an electrical charge, but it was published only in 1822.

In 1801, Giuseppe Piazza discovered Ceres, a 'planetoid,' or asteroid, as it came to be known.

In 1801, Johann Georg von Soldner, acting on Newton's assumption that light is a stream of particles, calculated the gravitational effect on light rays from distant stars passing close to the Sun, stating that the position of a star seen near the edge of the Sun should shift relative to where it is seen when the Sun is elsewhere in the sky by 0.84 arcsecond.  However, as Einstein pointed out, the angle is twice as large: "Half of this deflection is produced by the Newtonian field of attraction of the Sun, and the other half by the geometrical modification ('curvature') of space caused by the Sun" (Einstein, quoted in Wambsganss 2001:66).

In 1801, Gauss employed his 'least squares' approximation method, which fits a regression line to a set of data, to calculate the orbit of Ceres.
In 1801, Gauss's research into infinitesimal calculus and algebra culminated in the publication of Disquisitions arithmeticae.
In 1801, Joseph-Marie Jacquard invented the punched-card loom. [added 02/01/03]

In 1802, Wollaston discovered that the spectrum of sunlight is crossed by a number of dark lines (Wollaston 1802:365-386).

In 1802, Heinrich Wilhelm Matthias Olbers discovered Pallas, an asteroid in an orbit similar to the of Ceres, causing him to hypothesize that they were remnants of an exploded planet.  This would fill Kepler's gap and confirm Bode's law.  Two more asteroids were discovered in this area: In 1804, Juno by Karl Ludwig Harding, and, in 1807, Vesta by Olbers.

In 1803, L. Carnot, in Principes fondamentaux de l'équilibre et du mouvement, revised his 1783 book by simplifying the idea of 'geometric motions' to motions which "involve no work done on or by the system," along with the notions that "process consisted in the transition between successive 'states' of a system" and these transitions occur "in infinitesimal and reversible changes" (Gillispie 1976:74,75).

In 1803, Dalton , in "The Absorption of Gases by Water and Other Liquids," applied atomic theory to a table of atomic weights.  In the common and acceptable sense, an atom was merely "a term for a particle which was divisible only with the loss of its distinguishing characteristics" (Thackray 1976:543), and neither Dalton nor anyone else realized the implications of atomic weights.  There was no reaction to this paper which was only intended to explain why water treats different gases differently, that is, to defend his 1801 papers.

In 1803, Wollaston discovered the element 'palladium.' 

In 1804, Nicholas-Theodore de Saussure published a description of the action of photosynthesis.

In 1805, Friedrich Sertürner isolated morphine from the poppy plant.
In 1805, Alexander von Humboldt noted that species had not arisen at a single place.
In 1805, Ludolf Christian Treviranus said that spermatozoa were analogous to pollen.
In 1806, Louis Nicolas Vauquelin and Pierre Jean Robiquet isolated the first amino acid, 'asparagine,' from asparagus.
In 1806 and 1807, Laplace, in supplements to Traité de mécanique céleste, described his theory of the production of liquid surface energy in capillaries as the perpendicular inward attraction, exerted on the surface particles by the underlying ones, according to the formula p = K + ½ H (1/R + 1/R'), where K is a constant pressure, H is a constant on which all capillary phenomena depend, and R and R ' are the radii of the curvature of any two sections of the surface which are at right angles to each other.  Surface tension parallel to the surface does not exist.
In 1806, Gay-Lussac demonstrated that if an ideal gas expands without doing work, its temperature remains constant.
In 1806, Jöns Jacob Berzelius, in a book on animal chemistry, noted that muscle tissues contain lactic acid, previously found by Scheele in milk.
In 1806, Legendre, in "Nouvelles méthodes pour la détermination des orbites des comètes," invented, independent of Gauss, a least squares method and was the first to publish it.

In 1807 through 1812, Davy, in successive Bakerian Lectures, approached chemistry as if were the key to the ultimate mysteries of the Universe and concluded that "chemical properties were a function not simply of the components of a substance but also of their relative arrangements.  Thus he finally put it beyond doubt that carbon and diamonds were chemically identical; that neither all acids nor all alkalies contained oxygen; and that oxygen enjoyed no unique status as the supporter of combustion [as Lavoisier had hypothesized], but that heat was a consequence of any violent chemical change" (Knight 1976:602).  He revealed that alkalies and, later, earths were metallic oxides, isolated potassium, sodium, magnesium, calcium, strontium, and barium, obtained boron and silicon, and proved that chlorine and iodine are elements.  He also advanced the theory that hydrogen is generically present in acids, and classed chemical affinity as an electric phenomena.
In 1807, T. Young, in Lectures on Natural Philosophy and Mechanical Arts, coined the word 'energy,' for the fundamental quantity created by the heat which moved particles in D. Bernoulli's kinetic theory.  Also, Young presented experiments which verified that color was created by the wave theory of light and described the eye defect, now called 'astigmatism.'
In 1807, Robert Fulton ushered in the era of self-propelled ships with his construction of a commercially viable paddle-wheel steamboat. [added 02/01/03]

In 1808, Gay-Lussac ennunciated the 'Law of combining volumes,' which said that when gases combine they do so in small whole number ratios.

In 1808, Dalton, in New System of Chemical Philosophy, launched the chemical atomic theory, which "reduced all kinds of matter to a finite number of elements (only eighteen in those days)" (Cercignani 1998:203). He postulated the radical notion that atoms can neither be created nor destroyed and that all atoms of an element were identical.  He showed how "the laws of chemical combination demanded the existence of atoms, [and is] generally regarded as the founder of the atomic hypothesis" (Glashow 1991:101).  After this the main thrust of his work was in "providing experimental measurements of atomic weights of known chemical compounds" (Thackray 1976:543). [revised 02/01/03]

In 1808, Gauss, in Theoria motus corporum coelestium in sectionibus conicis solem ambientum, found methods of determining an orbit from at least three observations.  It also contained his presentation of the least squares method.

In 1809, Jean-Baptiste Monet de Lamarck, in Philosophy Zoologique, stated that heritable changes in 'habits,' or behavior, could be brought about by the environment, that acquired characters could be achieved by selective breeding, and that the use and disuse of parts could lead to the production of new organs and the modification of old ones.  His knowledge was much broader than E. Darwin's and he was the first important proponent of evolution, that is, that species, including man, were mutable over generations and adaptible to changed environments.

In 1809, T. Young applied wave theory to refraction and dispersion phenomena which led to a description in terms of transverse vibrations.  In turn, this led to raising questions about the nature of aether since it was assumed to be fluid-like: Fluids can't transmit transverse waves.

In 1810, Wollaston isolated a second amino acid, 'cysteine,' from a bladderstone.

Between 1810 and 1819, Gall published four volumes entitled Anatomie et physiologie du système nerveux en général, et du cerveau en particulier, avec des observations sur la possibilité de reconnoitre plusiers dispositions intellectuelles et morale de l'homme et les animaux, par la configuration de leurs têtes. This book established psychology as a biological science, but the popular application of his theories in the form known as 'phrenology,' i.e., every aspect of behavior had its own organ which correlated with prominences on the the skull, eventually was seen to be pseudoscience. "The list of prominent political, philosophical, and literary figures who took it seriously is astonishing and includes G. W. F. Hegel, Otto von Bismarck, Marx, Balzac, the Brontës, George Elliott, President James Garfield, Walt Whitman, and Queen Victoria..., as well as in the scientific writings of Auguste Comte, G. H. Lewes, Spencer, Chambers, and A. R. Wallace" (R. M. Young 1978). [added 02/01/03]

In 1811, Amedeo Avogadro proposed that equal volumes of gases at the same temperature and pressure contain the same number of molecules.  He used 'integral molecules' and 'elementary molecules' to denote what were later called the molecules of a chemical compound and the atoms of the elements of which it was composed.  Later physicists determined the number of atoms in a 'mole' to be 6.02552 x 1023, and called it Avogadro's number.  The reality of molecules came to be accepted by organic chemists after about 1860, but in the early twentieth century physicists still doubted their reality. In other words, molecules are "recurrent groupings of atoms" (Hoffman and Torrence 1993:16). [revised 02/01/03]

In 1811, Berzelius simplified chemistry through his suggestion that they be represented by the first letter of each elements Latin name, with the addition of the second letter when necessary.  To indicate the proportions in a compound he wrote the appropriate number as subscript.

In 1811, Pierre Louis Dulong discovered nitrogen trichloride, a spontaneously explosive oil. 

In 1811, Siméon-Denis Poisson, in "Sur la distribution de l'électricité à la surface des corps conducteurs," found Laplace's integral V function "by expressing the integrands as series.  [Later this was called the 'potential function.']  Poisson's V is the analytic form of Cavendish's 'electrification' and Volta's 'tension. ' It is more supple than either, for it permits the statement of the classical problems of electrostatics-finding the distribution of electricity and the resultant forces-in full generality" (Heilbron 1979:499).  Poisson attributed to electricity the material properties of actual fluids.

In 1811, Fourier, in a paper on heat diffusion, invented the formula for a trigonomic series by which any repeated physical event can be defined by its phase and its amplitude and represented as a set of simple wave forms.  As this was incapable of expressing initial conditions in infinite bodies, he also created an integral theorem.  Today these are known as Fourier series and Fourier integrals.

In 1812, Georges Cuvier, in Discours sur les révolutions de la surface du globe, maintained the stratigraphic succession proved that fossils occur in the chronological order of creation: fish, amphibians, reptiles, and mammals.  He applied the new Jussieu approach to animals, but read the paleontological evidence to justify a succession of cataclysms, each followed by creation of new flora and fauna.  At this time paleotology was still a branch of geology.  Cuvier supported the idea of the fixity of species and opposed Lamarck's conception.

In 1812, Berzelius, in the second volume of his textbook Lärbok I kemien and in subsequent volumes, in journals, and in his annual reports, denied the generic and hierarchical classification of chemicals and showed that acidity and basicity are composed of specific components, for example, a certain degree of electro-negativity or positivity.  Similarly, in his theory of salts, the oxides of qualitatively opposed radicals lay on the same ontological plane.  The specificity of the radicals, not the degree of oxidation, became the chief determinant of properties.  He also drew the line between organic and inorganic, showing that in the former "a sufficiently large number of atoms entered...to permit the manifestation of apparent transitions occasioned by relatively small differences in composition" (Melhado 1981:123).

In 1813, Davy published the first book on agricultural chemistry.

In 1814, Joseph von Fraunhofer devised a primitive spectroscope by allowing light to pass through a narrow slit and then a prism, obtaining Newton's rainbow with numerous sharp, narrow dark lines in fixed positions.

In 1815, Konstantin Sigizmundovich Kirchhof reported that wheat glutin is capable of being converted to dextrin and sugar.

In 1815, William Prout proposed that the atomic weights of elements are multiples of that for hydrogen.

In 1816, Augustin Jean Fresnel showed that diffraction and interference can be explained in terms of the wave theory of light. 

In 1816, Fresnel and Dominique François Arago discovered that perpendicular beams of polarized light do not interfere with each other.  This led to the transverse theory of light waves, which replaced the longitudinal theory. 

In 1817, Christian Heinrich Pander described three germ layers in chick embryos.

In 1817, Berzelius discovered the element 'selenium' and, in 1828, 'thorium.'  Also in 1817, in Berzelius' laboratory, J. A. Arfwedsen isolated 'lithium.'  Also, in Berzelius' lab, in 1830, N. G. Sefström found 'vanadium.'

In 1818, Étienne Geoffrey Saint-Hilaire defined the concept of 'homologous,' that is, having the same evolutionary origin, e.g., a wing and an arm, although he didn't come up with the word until 1825.  A friend of Lamarck's, he found numerous evidences of the environmentally-induced disuse of parts.  He "tried to combine continuity of descent with discontinuity of form by the hypothesis that new species and higher categories start from the occasional appearance of monsters capable of flourishing in an appropriate environment" (Wright 1948:916).

In 1818, W. C. Wells enunciated the principle of natural selection among human populations, suggesting that African populations are selected for their relative resistance to local diseases.

In 1818, Michael Faraday began a series of successful experiments on alloys of steel which were, however, not commercial because of the alloyed materials.  Later work on steel alloys is based on Faraday's work.

After 1818, Gauss was employed doing geodesic surveys where, aside from writing numerous papers on differential geometry, he invented the 'heliotrope,' a device used to measure distances by means of reflected sunlight.  One of the papers had to do with 'potential theory,' and another with 'Gaussian curves.'

In 1819, Dulong and Alexis Thérèse Petit, in "Recherches sur quelques points importante de la théorie de la chaleur," determined that the atomic weights of chemical elements were inversely proportional to their specific heats and that "the atoms of all simple bodies have exactly the same capacity for heat" (Dulong and Petit, quoted in Crosland 1976:241).  This is known as the law of constant atomic heats.

In 1819, Arthur Schopenhauer, in Welt als Wille und Vorstellung, called "the genital organs the focus of the will [adding that] indeed, one may say man is incarnate sexual instinct, since he owes his origin to copulation and the wish of his wishes is to copulate" (Schopenhauer 1819:314).

In 1820, Lamarck described the origin of living things as a process of gradual development from matter.

In 1820, Christian Friedrich Nasse said that while hemophilia occurs only in males, it is passed through the female line.
In 1820, J. B. Caventou and P. J. Pelletier isolated quinine from cinchona bark.
In 1820, Hans Christian Øersted initiated the study of electromagnetism by placing a needle parallel to a wire conducting electric current and discovering that this produces a magnetic field that curls around the wire.  He gave as explanation for this action of a magnetic pole and an electric current, an apparently heterogenous pair, the "impetus of [their] contending powers" (Øersted, quoted in Heilbron 1981:199).
Later in 1820, André Marie Ampère published his conjecture that "the fundamental [electrical] force is a rectangular push or pull between elements of current: attraction between elements moving parallel, repulsion between ones moving in opposite directions."  Current is visualized as a sequence of squirts, a "succession...of decompositions and recombinations of the fluid formed by the union of the two electricities" (Ampère, quoted in Heilbron 1981:197).  He further hypothesized that "a magnet owes its power to elementary current loops perpendicular to its axis" (Ibid.:200); i.e, all magnetism can be attributed to electric currents.  He also originated the idea of the electric telegraph.

In 1821, Fresnel stated laws making possible the calculation of the intensity and polarization of reflected and refracted light.  According to his law of reflection, if the transition between the air and a reflective medium "is absolutely abrupt, the light is completely plane polarized...., if the transition is gradual, the light is elliptically polarized" (Adam 1930:7).  He also devised a method to produce circularly polarized light. 

In 1821, Wollaston explained the interactions of Ampère's wires "upon the supposition of an electromagnetic current passing round the axis of [each]" (Wollaston, quoted in Heilbron 1981:200).  Davy adopted Wollaston's interpretation.

In 1821, Faraday, published "History of the Progress of Electro-Magnetism," in which he accepted Wollaston's interpretation of electricity.  He also demonstrated that the elementary phenomena was "the [continuous] rotation of a pole about a wire, or of a wire about a pole, [using] apparatus that...allowed motions over 360 degrees" (Heilbron 1981:201).  This rendered possible the production of continuous mechanical motion by electricity, i.e., the electric motor.

In 1821, John Herapath, in "A mathematical inquiry into the causes, laws, and principle phenomena of heat, gases, gravitation, etc.," proposed a kinetic theory of heat, i.e., it is movement, not a substance.

In 1821, Augustin-Louis Cauchy, in his Cours d'analyse, established the calculus on the formalism of his concept of analytic function, divorcing the idea from any reference to geometrical figures or magnitudes and unequivalently stating that the limit must be zero for higher order infinitesimals.

In 1821, Jean François Champollion, employing the Rosetta Stone, established the principles for deciphering Egyptian hieroglyphics. T. Young, also employing the Rosetta Stone, deciphered the demotic script.

Between 1822 and 1824, John Goss, Alexander Seton, and T. A. Knight, each independently, observed the segregation of a recessive trait in peas, but kept no records of later generations.

In 1822, Eilhard Mitscherlich, in "Om Förhållandet einellan Chemiska Sammansättningen och Krystalliformen hos Arseniksyrade och Phosphorsyrade Salter" (On the Relation Between the Chemical Composition and the Crystal Form of Salts of Arsenic and Phosphoric Acids), noted that "certain elements have the property of producing the same crystal form when in combination with an equal number of atoms of one or more common elements....  The crystal form does not depend on the nature of the atoms, but only on their number and mode of combination" (Mitscherlich, quoted in Szabadváry 1976:426).  He arranged these in groups and called those in the same group 'isomorphous.'

In 1822, Fourier, in Théorie analytique de la chaleur, expanded his 1811 paper and made numerous additions, including time-dependent equations for heat flow and the formulation of physical problems as boundary-value problems in linear partial differential equations.

In 1823, Faraday discovered the liquifaction of chlorine. 

In 1823, Poisson, in "Sur la chaleur des gas et des vapeurs," worked out a "quantitative theory of gases, in which the repulsion between atoms was attributed to the action of 'atmospheres' of caloric surrounding the atoms" (Brush 1964:7). 

In 1823, János Bolyai invented a non-Euclidean geometry by assuming that one could be constructed without the parallel postulate.  It was published in 1832.

In 1824, Marie-Jean-Pierre Flourens, in Recherches experimentales sur les propriétés et fonctions du systèm nerveux dans les animaux vertébrés, said that while every organ of the brain had its specific function these parts functioned as a whole and that all perceptions could concurrently occupy the same places in the forebrain. He was strongly opposed to Gall's phrenology. [added 02/01/03]

In 1824, Nicolas Léonard Sadi Carnot , in Réflexions sur la puissance motrice du feu et sur les machines propres à développer cette puissance, showed in a series of operations, known as Carnot's cycle, that even under ideal conditions a steam engine cannot convert into mechanical energy all the heat energy supplied to it.  His theory was founded on the concept that heat is a substance, likening the operation of the heat engine to that of "a column-of-water device in which a quantity of water falling through a fixed distance from a given height produces an invariable quantity of motive power, the water being fully transferred from its original height to a reservoir at a lower level" (Buchwald 1976:378).  Thus, heat, or calorique, a weightless fluid, could not be created nor destroyed.

In 1824, Neils Hendrik Abel proved that the general quintic equation was insoluble by radicals.  The 'Abelian group' is named in his honor. 

In 1825, Jean Baptiste Bouillard established the location of the language function, which in fact accorded with Gall's phrenology, in the anterior cortical lobe and that there could be paralysis of this function without paralysis of the limbs.
In 1825, Christian Leopold von Buch concluded that varieties may become species through being segregated.
In 1825, George Poulett Scrope, in Considerations on Volcanos, wrote that all lava formations could be accounted for by volcanic action of an intensity no greater than current eruptions.
In 1825, Øersted isolated aluminum.
In 1825, Faraday discovered benzene.

In 1825, the Stockton and Darlington Railway began steam-powered freight and passenger service in England. 

About 1826, Robert Grant, August Schweigger, and Friedrich Tiedemann declared themselves in favor of a common origin for both plants and animals.

In 1826, Nikolai Ivanovich Lobachevsky announced the development of a system of hyperbolic geometry in which Euclid's fifth postulate was replaced by one allowing more than one parallel line through a fixed point.
In 1826, Olbers expressed the paradox that if the Universe was infinite, the night sky would be bright with stars.
In 1827, Georg Simon Ohm discovered that the ratio of the potential difference between the ends of a conductor and the current flowing through it is constant, and is the resistence of the conductor.

In 1827, Robert Brown noticed random movement of microscopic particles contained in the pollen from plants when suspended in fluid.  This is known as Brownian movement. [revised 02/01/03]

In 1828, Karl Ernst Ritter von Baer, having examined the fetal anatomy of numerous species, published the view that all animals have three germ layers and that that the ontogeny of embryos proceeds from initial homogeneity to heterogeneity by stages similar to other young animals, but not by the recapitulation of the adult forms of lower animals.
In 1828, Friedrich Wöhler synthesized urea by heating ammonium cyanate.  This was the first synthesis of an organic compound from inorganic material.
In 1828, William Rowan Hamilton, in "Theory of Systems of Rays,", predicted the existence of conical refraction and developed general equations of motion in optics which related Kepler's light rays to Young's particles.

In 1828, William Nicol invented a polarizing prism made from two calcite components.

In 1828, George Green, in An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism, coined the term potential function to denote the sum of the forces acting on a material point in a system and "expressed by a partial differential of a certain function of the coordinates which define the point's position in space" (Green 1828:9); in other words, electrical potential "suffices to determine both the forces and the distribution of electricity on conducting bodies and permits dispensing with Poisson's postulate of an electrical layer of finite depth" (Buchwald 1976:376).  Also, in this essay was "the formula connecting surface and volume integrals, now known as Green's theorem" (Wallis 1978:199).
In the late 1820s, Joseph Henry, by vastly increasing the number of wire coils around a magnet, created a powerful electromagnet.

In 1829, Charles Lyell, in Principles of Geology, built a synthesis on the methodological limitation that the past could be studied only by analogy to what natural agencies, given enough time, could accomplish in the present.  His opinion that there was uniformity in the causes of change--rather than catastrophic floods--"implied that they must forever produce an endless variety of effects, both in the animate and inanimate world" (Lyell, quoted in Hardy 1965:62).  In Thomas Huxley's opinion, Lyell's work bore the primary responsibility for smoothing C. Darwin's path.  Wallace credits Lyell's idea that the surface of the earth was in a continual state of slow modification for making obvious to him that life must be continually adjusting to these changed conditions.
In 1829, Thomas Graham, in "A Short Account of Experimental Researches on the Diffusion of Gases Through Each Other, and Their Separation by Mechanical Means," contained the essentials of what became known as Graham's Law: "The diffusion or spontaneous intermixture of two gases in contact is effected by an interchange in position of indefinitely minute volumes of gases, which volumes are not necessarily of equal magnitude, being, in the case of each gas, inversely proportional to the square root of the density of that gas, [i.e.,] diffusion takes place between the ultimate particles of gases, and not between sensible masses" (Graham 1833. "On the Law of the Diffusion of Gases," quoted in Kauffman 1976:493).  He also pointed out that "mixture of gases could be separated by diffusion, a process employed during World War II..., to separate the fissionable isotope uranium 235 from the nonfissionable isotope uranium 238" (Kauffman 1976:495).
In 1829, Johann Döbereiner began the rationalization of the chemical elements when he observed triadic groups whose central member was the arithmetic mean of the two outer members.
In 1829, James Mill published the first volume of Analysis of the Phenomena of the Human Mind in which he said that resemblance can be reduced to co-occurrence, a special case of what he called synchronous order.

In 1830, Robiquet and others discovered the hydrolytic splitting of the glucoside, 'amygdalin.'

In 1830, Giovanni Battista Amici traced the growth of the pollen tube down through the 'style' and into the ovule of the flower.

In 1830, Joseph Lister showed lenses which corrected for aberration.
In 1830, Gauss, in Principia generalia Theoriae Figurae Fluidorum in statu Aequilibrii, invented a single expression for surface tension which aggregated all the potentials arising from the interaction between pairs of particles.
In 1830, Macedonio Melloni invented the thermocouple, by which the transmission of heat by various substances can be measured.
In 1830, Auguste Comte, in Cours de philosophie positive, maintained that intellectual development consisted in three stages: the theological, in which events are attributed to supernatural forces; the metaphysical, in which natural phenomena are attributed to 'fundamental' forces; and the positive, in which phenomena are explained by observation, hypothesis, and experimentation. He also coined the words 'sociology' and 'altruism.'

In 1831, Brown discovered the cell nucleus in the course of a microscopic examination of orchids. [revised 02/01/03]

After 1831, Friedlieb Ferdinand Runge, through the distillation of coal tar and extraction of its parts, isolated and named carbolic acid, leucol, pyrol, and cyanol. From cyanol he produced aniline black which he patented in 1834. [added 02/01/03]

In 1831, Faraday , in the first in a series of Experimental Researches in Electricity, discovered the means of producing electricity from magnetism, i.e., electromagnetic induction, the generation of an electric field by a changing magnetic field.  Using a 'transformer ring,' an iron ring wrapped in a wire coil, he was able to induce a transient current in a galvanometer.  This is the principle of the dynamo.  He speculated that electromagnetic phenomena might be situated in the aether.

In 1831, Franz Ernst Neumann, in "Untersuchung über die specifische Wärme der Mineralien," extended the law that the specific heats of elements vary inversely as their atomic weights to include compounds and determined that the molecular heat of a compound is equal to the sum of the atomic heats of its constituents.

In 1831, Berzelius proposed the name 'isomerism' for different compounds with same chemical composition, such as that discovered by Wöhler.

In 1832, G. G. Hällström said that one should hear beats of the harmonics of the tones f1and f2; however, this was not confirmed until 1856 when Hermann Ludwig Ferdinand von Helmholtz did so.

In 1832, W. Hamilton, in the third supplement to "Theory of Systems of Rays," explained how the characteristic function in optics made the optical length a function of variable initial and final points.  When applied to Fresnel's wave surface, he was able to predict that "a single ray incident in the correct direction on a biaxial crystal should be refracted into a cone in the crystal and emerge as a hollow cylinder" (Hankins 1976:88).  This was verified experimentally by Humphrey Lloyd

In 1832, Évariste Galois, in a letter published posthumously, invented the concept of the group as the symmetries of a polynomial equation and "sketched the connection between groups and polynomial equations, stating that an equation is soluble by radicals provided its group is soluble" (Stewart 1989:xxii). 

In 1833, Johannes Peter Müller published his discovery that sensation is not controlled by the stimulus but rather is dependent on the particular sense organ involved: Each sensory nerve produces its own specific sensation, e.g., any stimulation of the optic nerve results in a sensation of light.
In 1833, Marshall Hall described the mechanism by which a stimulus can produce a response independent of both sensation and volition, and coined the term 'reflex.'
In 1833, Graham, in "Researches on the Arseniates, Phosphates, and Modifications of Phosphoric Acid," elucidated the differences between the three phosphoric acids, triphosphate, biphosphate, and phosphate of water, and established the concept of polybasic compounds, i.e., "a class of hydrated acids with more than one proportion of water replacable by a basic metallic oxide so that several series of salts could be formed" (Kauffman 1976:493).

In 1833, W. Hamilton, in "On a General Method of Expressing the Paths of Light and of the Planets by the Coefficients of a Characteristic Function," explained how Fermat's principle of least time led to the law of least action and pointed out that "in mechanics the action is only a local minimum or local maximum.  The essential property...was not that of being greater or less but that of being stationary under small variations in motion" (Park 1990:348); i.e., "the Law of Stationary Action" (Hamilton 1833:316-318).  This he later extended to dynamics, often called 'Hamiltonian mechanics.'  "The classical Hamiltonian expresses the energy of a dynamical system in terms of coordinates q and momenta p, and therefore takes on a continuous set of values.  It cannot lead to discrete energy levels.  For this reason, the Hamiltonian H is replaced in quantum theory by the Hamiltonian operator Hop" (Prigogine 1996:133). In fact, for all its elegance, the Hamiltonian method was little used until the rise of quantum mechanics when it turned out to be "the one form of classical mechanics that carried over directly into the quantum interpretation" (Hankins 1976:89).
In 1833, Gauss invented the electric telegraph.
In 1833, Charles Wheatstone invented the 'stereoscope,' revealing the dependence of visual depth perception upon binocular double vision.

In 1834, Berzelius, in Annalen der physikalisches Chemie, reported finding organic matter, humic acid, in a meteorite.  Such meteorites are called 'carbonaceous chondrites.' 
In 1834, Anselm Payen and Jean-François Persoz isolated 'diastase' from barley malt and postulated the importance of enzymes in biology.

In 1834, Faraday , in the seventh series of Experimental Researches, having proved the identity of electricities, went on to add another link in the chain of the convertibility of forces by establishing two fundamental laws of electrochemistry or electrolysis, i.e., the passage of electricity through ionic solutions: "The amount of chemical change produced is proportional to the quantity of electricity passed [and] the amount of chemical change produced in different substances by a fixed quantity of electricity is proportional to the electrochemical equivalent of the substance" (Dictionary of Physics 2000:167).  Moreover, he proved to his own satisfaction that these changes were not effected by action at a distance.  To prepare the way for a successful challenge to the prevalent theory, Faraday introduced a new and neutral nomenclature.  "Instead of poles, which implied centers of force, [he] used the term 'electrode,' which had no such implication.  Similarly 'cathode,' 'anode,' 'electrolysis,' 'electrolyte,' 'anion,' and 'cation' were merely descriptive terms.  William Whewell...was the source of most of these neologisms" (Williams 1976:537).

In 1834, John Scott Russell, in the course of studying waves, observed a solitary wave, which "consists in a motion of translation of the whole mass of the fluid from one place to another, to another in which it finally reposes" (Russell 1844:317).  Such ' waves of translation' led to the idea of a soliton, or solitary wave-state that is a solution of certain physical propagation equations. 
In 1834, Charles Babbage designed a programmable mechanical calculating machine, or 'analytical engine,' that could carry out arithmetic operations specified on punch cards and choose the sequence of operations.  Although the design was never built, Augusta Ada Byron wrote programs to demonstrate its potential power. 

In 1835, Berzelius suggested the name 'catalysis' for reactions which occurred only in the presence of some third substance, "as one designates the decomposition of bodies by chemical affinity analysis" (Berzelius, quoted in Leicester 1976:95).  He classified fermentation as a catalyzed reaction.

In 1835, George Biddell Airy calculated the form of a diffraction pattern produced by a circular aperture.  He also designed a cylindrical lens for correcting astigmatism.

In 1835, Jean Élix Benjamin Valz, Friedrich Bernhard Gottfried Nicolai, and Niccolo Cacciatore, each independently, conjectured that a trans-Uranian planet caused the otherwise inexplicable discrepancies in the historical record of the orbits of both Halley's comet and Uranus.

In 1836, Theodor Schwann reported the action of 'pepsin' and described its properties.

In 1836, Wilhelm von Humboldt, in Über die Verschiedenheit des Menschlichen, published posthumously, maintained that, "for an individual, learning is largely a matter of Weidererzeugung, that is, of drawing out what is innate in the mind" (Chomsky 1965:51). 

In 1837, Heinrich Gustav Magnus determined that carbon dioxide released in the lungs had been carried there by blood and that more oxygen and less carbon dioxide was contained in arterial than in venous blood. (Magnus 1837)

In 1837, René Dutrochet observed that chlorophyll is necessary for photosynthesis.
In 1837, Hugo von Mohl described 'chloroplasts' as discrete bodies within the cells of green plants.
In 1837 and 1838, Schwann, Charles Cagniard de la Tour, and Friedrich Traugott Kützing, working independently, said that "yeast was a living organism which was responsible for fermentation.  This began a lengthy debate over whether fermentation was a chemical or a vital process" (German Life Science Information Service 1993:6).
In 1837 and 1838, Faraday, in "On Induction," the eleventh and twelfth in the series of Experimental Researches, presented a coherent and general theory of electricity.  "Faraday, in his mind's eye, saw lines of force traversing all space where the mathematicians saw centres of force attacting at a distance: Faraday saw a medium where they saw nothing but distance: Faraday sought the seat of the phenomena in real actions going on in the medium, they were satisfied that they found it in a power of action at a distance impressed on the electric fluids....  Faraday's methods resembled those in which we begin with the whole and arrive at the parts by analysis, while the ordinary mathematical methods were founded on the principle of beginning with the parts and building up the whole by synthesis" (Maxwell 1873:ix).
In 1837, Ralph Waldo Emerson observed, "The ancient precept, 'Know thyself,' and the modern precept, 'Study nature,' become at last one maxim" (Emerson 1837:56). He also said that life consists of what a man is thinking all day. 

In 1838, Mattias Jakob Schleiden put forward the theory that plant tissues are composed of cells, and recognized the significance of the nucleus. 
In 1838, Purkinje found that nerve cells consist of two parts, later named axons and dendrites. About this time, he also coined the term 'protoplasm,' and, with Mohl, established that the protoplasm is the living contents of a cell.
In 1838, Carlo Matteucci, in "Sur le courant électrique ou presque de la grenouille," recorded the production by a muscle of an electric current with a galvanometer. [revised 02/01/03]

In 1838, Friedrich Bessel solved the sidereal trigonomic parallax problem in the course of working with 61 Cygni, a nearby star with a large 'proper motion,' or transverse velocity.  This was closely followed by Thomas Henderson, working with Alpha Centuri, in 1839, and Frederick von Struve, working with Vega, in 1840.  At this point, the isolation of the Solar System was realized.
In 1838, Gerardus Johannes Mulder published Berzelius' term 'protein.'

In the late 1830s, Richard Owen distingushed between 'homology' and 'analogy:' A wing of a bird and a bat are analogous since for flight one has feathers and the other membrane, but the bones and musculature are homologous.  He supported the fixity of species.

In 1839, Schwann, in Mikroskopische Untersuchungen über die Uebereinstimmung in der Struktur und dem Wachstume der Tiere und Pflanzen, claimed that animal tissues are composed of cells with nuclei.  It concludes with a methodological discussion in which he says that a teleological explanation is admissible only when a physical explanation is unattainable and in that case both operate "like physical forces in service to strict laws of blind necessity" (Schwann 1839:).

In 1839, Mohl described the appearance of the cell plate between the daughter cells during cell division, or 'mitosis.'

In 1839, Johann Schoenlein, using a microscope, discovered a microbial parasite of humans, Trichophyton schoenleinii, which causes ringworm of the scalp.
In 1839, Christian Swann discovered the existence of ozone.
In 1839, Louis Jacques Mandé Daguerre made public his invention of the first photographic process. "The first daguerrotype of the disk of the Sun was obtained by two physicists in Paris in 1845" (Gribbin and Gribbin 2000:54), and subsequent improvements in emulsion speeds had enormous repercussions for astronomy.
In 1839, George Boole developed analytic transformations, the basis of Boolean algebra, which is of fundamental importance in the study of the foundations of mathematics, logic, and computer simulation.

In 1840, T. L. Hünefel , in Der Chemismus in der thierischen Organization, reported his observation of crystals in the blood . [revised 02/01/03]
In 1840, Whewell introduced the word 'scientist.'  Until then, science had retained its medieval denotation, truth derived from first principles, or moral science, as opposed to natural philosophy.
In 1840, Louis Agassiz published a demonstration of the existence of a glacial epoch in the temperate zones.
In 1840, Christian Friedrich Schönbein isolated 'ozone,' naming it from the Greek word ozein, to smell.
In 1840, Berzelius suggested the name 'allotropy' for the occurence different forms of the same element.

In 1841, Albrecht von Kölliker showed that spermatozoa are sex cells which arise by a transformation of cells in the testes.

In 1841, Julius Robert Mayer, working with established experimental results, derived the general relationship between heat and work, which is the first law of thermodynamics, a form of the law of conservation of energy: The form of energy can be changed, but it can neither be created nor destoyed.  The idea of energy, a thing without weight which could neither be seen nor felt and had a constant value through many transformations, was not quickly adopted.

In 1842, Johann Japetus Steenstrup described the alternation of sexual and asexual generations in animals and plants.  In some jellyfish,  the 'medusoid' stage usually reproduces sexually, giving birth to the 'polyp,' or 'hydroid,' stage, which reproduces asexually.  Ferns have a 'sporophyte' generation which produces spores which give rise to a 'gametophyte' generation which reproduces sexually (Hale and Margham 1991:26).

In 1842, Christian Doppler developed the theory that the frequency of energy in the form of the form of waves changes depending on the motion of either the sender or the receiver.

In 1842, William Thomson, in "On the Uniform Motion of Heat in Homogenous Solid Bodies, and its connection with the Mathematical Theory of Electricity," concluded that "any two theories dealing with the same phenomena...cannot conflict if their most elementary laws can be connected mathematically" (Buchwald 1976:376).
In 1843, Justus von Liebig speculated that organic acids, such as malic, tartaric, and oxalic, are intermediates in a plant's production of carbohydrates.
In 1843, James Braid suggested changing the term 'animal magnetism' to 'hypnotism,' from the Greek hypnos, to sleep.
In 1843, James Prescott Joule, working without awareness of Mayer's proof, demonstrated experimentally the "strict equivalence of the heat produced [by an induced current] and the mechanical work spent in the operation..., thus [obtaining a] determination of the coefficient of equivalence" of heat and work (Rosenfeld 1976:182).  "Thus it is that order is maintained in the universe-nothing is destroyed, nothing ever lost, but that the entire machinery, complicated as it is, works smoothly and harmoniously" (Joule, quoted in Buchwald 1976:380).  One crucial aspect is Joule's conception of latent heat, the heat absorbed or released when a substance undergoes a phase change without a temperature change, e.g., water into ice or into steam.  Latent heat is thought of as "the work done against the internal, molecular forces of a body [which] then store it in the resulting molecular configuration, [or] 'attraction through space,' in Joule's terminology" (Buchwald 1976:381).  He did not publicly announce his discovery until 1847 in a newspaper article entitled "On Matter, Living Force, and Heat."
In 1844, Karl Friedrich Wilhelm Ludwig showed that waste products are passively filtered by the 'Malpighian corpuscle' in the kidney and then concentrated as they pass through the tubules.

In 1844, Robert Chambers, anonymous author of Vestiges of the Natural History of Creation, wrote that "mental action...passes at once into the category of natural things.  Its old metaphysical character vanishes..., and the distinction usually taken between physical and moral is annulled" (Chambers, quoted in Gillispie 1951:157).  Chambers  developed his "evolutionary theory as a metaphorical extension of von Baer's principle" (Gould 1977:110).  He was crucially influenced by Comte's positivism.
In 1844, C. Darwin wrote, but didn't publish, an essay presaging the theory of the origin of species.

In 1844, Samuel Finley Breese Morse demonstrated a telegraph, using a code of his own invention, similar to semaphore. 
In 1845, J. Dzierzon reported that among bees the drones hatch from unfertilized eggs while workers and queens are from fertilized eggs.
In 1845, Adolf Wilhelm Hermann Kolbe synthesized acetic acid.

In 1845, Jacques-Joseph Moreau maintained that mental illness with its delusions and hallucinations was not the reult of stimulation, but rather the result of "a diminution of intellectual function and a disproportionate development of vestigial psychic activities" (Ellenberger 1970:290).

In 1845, Faraday, writing his nineteenth series of Experimental Researches in response to a query by W. Thomson, described the 'effect' made by rotating a plane of polarized light through a transparent body glass in a strong magnetic field; i.e., "the angle of rotation [is] directly proportional to the strength of the magnetic force" (L. Williams 1976:538).  "That which is magnetic in the forces of matter has been affected, and in turn has affected that which is truly magnetic in the force of light....  The magnetic forces do not act on the ray of light directly and without the intervention of matter, but through the mediation of the substance in which they and the ray have a simultaneous existence" (Faraday 1845:paragraphs2146n2,2224).  That the magnetic force acts through glass suggested to Faraday that all materials "pass onward electrical lines of force-in Faraday's terminology, all are dielectrics.  Moreover, each material transmits the lines of force with a characteristic degree of efficacy, which Faraday called its specific inductive capacity" (Fisher 2001:380).  Subsequent Experimental Researches and a final article in 1852, "On the Physical Character of the Lines of Magnetic Force," were focused on the reality of the lines of force as represented by the curves of magnetized iron filings, rather than the affected materials, and formed the background for James Clerk Maxwell's 'field' formulation.

In 1845, W. Thomson, in "On a Mechanical Representation of Electric, Magnetic, and Galvanic Forces," on the basis of the Faraday effect, linked electrical and magnetic "forces to the internal processes of a single medium...; [i.e., they, though different phenomena,] were linked to a common element" and were mechanically, i.e., formally, analogous (Buchwald 1976:377).

In 1845, Mayer published the suggestion that the Sun could maintain its heat for millions of years if it were fueled by a steady supply of asteroids.

In 1846, William Morton demonstrated the effective use of ether as an anesthesia.

In 1846, Carl Gustav Carus published Psyche, which begins, "The key to the knowledge of the nature of the soul's conscious life lies in the realm of the unconscious....  The first task of  a science of the soul is to state how the spirit of Man is able to descend into these depths" (Carus, quoted in Ellenberger 1970:207).

In 1846, Ascani Sobrero discovered nitroglycerin. [added 02/01/03]

In 1846, Johann Gottfried Galle discovered the planet Neptune where Urbain Jean Joseph Le Verrier and, independently, John Couch Adams had predicted that a planet would be found.  Their predictions were based on perturbations in the orbit of Uranus. Bode's law broke down in the case of Neptune.
In 1846, Henry Creswicke Rawlinson published his deciphering of the cuneiform of the Behistun Inscriptions.

In 1857, Pasteur demonstrated that lactic acid fermentation is carried out by living bacteria.

In 1847, K. B. Reichert saw under a microscope blood which consisted of tetrahedral crystals and went some way toward demonstrating that it is protein (Reichert 1849). [added 02/01/03]

In 1847, Henry Bence-Jones discovered distinctive proteins in the urine of myeloma patients.[added 02/01/03]

In 1847, Flourens discovered the anesthetic properties of chloroform. [added 02/01/03]

In 1847, W. Bergmann pointed out that populations of warm-blooded species living in cool climates tend to be larger on average than members of the same species living in warmer climates because the surface area to volume ratio in the larger animals is less and, therefore, heat loss is reduced.

In 1847, A. Derbés observed the progressive lifting of the egg's vitelline membrane which begins at the point of sperm entry in the course of fertilization.

In 1847, James Esdaile made the first systematic use of hypnotism for anesthetizing surgical patients.
In 1847, Hermann Ludwig Ferdinand von Helmholtz , in "Über der Erhaltung der Kraft," formulated the law of the conservation of energy in an equation which expresses the most general form of the principle.  "Science [Helmholtz began] views the world in terms of two abstractions, matter and force.  The goal of science is to trace phenomena to their ultimate causes...; such ultimate causes are unchangable forces [which we can know] virtually a priori.  If we imagine matter dispersed into its ultimate elements, then the only conceivable change which can occur in the relationship is spatial.  Ultimate forces, then, must be moving forces radially directed.  Only the reduction of phenomena to such forces constitutes an explanation to which we may ascribe the status of 'objective truth'" (Turner 1976:243-244).
In 1847, Lambert Babo said that the addition of a solute to liquid vapor decreases the vapor pressure proportional to the amount of the solute.
In 1847, Augustus de Morgan published Arithmetical Books From the Invention of Printing to the Present Time.  Being Brief Notices of a Large Number of Works Drawn up From Actual Inspection, the earliest significant work of scienntific bibliography.

In 1848, Emil Du Bois-Reymond ,in the first volume of Untersuchungen über tierische elektrizität, demonstrated that the signal propagated along a peripheral nerve was a wave with a negative electrical charge and hypothesized that the impulse consisted in the rearrangement of molecules. [revised 02/01/03]
In 1848, Louis Pasteur discovered molecular dissymmetry, or chirality.  Later, he coined the distinction between users and non-users of oxygen, 'aerobic' and 'anaerobic.'
In 1848, Claude Bernard discovered the glycogenic function of the liver.
In 1848, Müller showed that one of the biological mechanisms necessary for human speech is a superlaryngeal vocal tract.
In 1848, W. Thomson, in "On an Absolute Thermometric Scale, Founded on [N.] Carnot's Theory of the Motive Power of Heat, and Calculated From the Result's of Regnault's Experiments on Steam," proposed what, after 1892, became known as the 'Kelvin scale,' after the title bestowed on him by the British government.

In 1848, Armand Hypolite Louis Fizeau, applying the Doppler effect to a moving light source, described the 'redshift' and 'blueshift' effects: The amount of the shift to red depends on the speed with which the light is receding from us, and vice-versa.

In 1849, Fizeau, "using a rotating toothed wheel to break up a light beam into a series of pulses,...made the first non-astronomical determination of the speed of light (in air)..., 313,300 km s-1" (History of Optics 2001:4). 

In 1849, Édoard Albert Roche stated the maximum value that distance imposes on the diameter of a satellite of a planet.  This limit explains the proximity of ring systems to planets.
In 1850, Franz von Leydig discovered interstitial cells in the connective tissue of the testes.
In 1850, Helmholtz measured the velocity of the impulse in the sciatic nerve of a frog.



In 1850, Jean Baptiste Boussingnault demonstrated that plants need only nitrogen from the soil and obtain carbon from the atmosphere.

In 1850, Runge, in Zur Farbenchemie: Musterbilder für Freunde des Schöne, demonstrated the separation of inorganic chemicals by their differential adsorption to paper. This is forerunner of chromatographic separations. [added 02/01/03]

In 1850, Rudolph Julius Emanuel Clausius, generalizing N. Carnot's principle, introduced the concept of 'entropy,' a measure of disorder in a system.  This, the 'second law of thermodynamics,' states that entropy can never decrease in a closed system, and will increase until it comes to a state of thermodynamic equilibrium where it must remain; i.e., all particles of gases will move randomly with equal average energy.  It is "law of nature which says that things wear out.  [Another] expression of the second law...is that heat cannot flow from a cold object to a hotter object of its own volition" (Gribbin 1998b:359).  Thus was introduced irreversibility, i.e., time's arrow, to classical physics.

In 1850, Jean Bernard Léon Foucault, using a rotating mirror, determined the speed of light in the air as 298,000 km s-1 and slower than that in stationary water. 

In 1851, Helmholtz invented the 'opthalamoscope,' a small instrument which when pressed against the eye enables the vessels to be seen.

In 1851, Foucault demonstrated that a pendulem's swing, seen relative to the Earth, would gradually precess.  This is evidence of the the Earth's rotation.

In 1851, Samuel Schwabe announced his discovery of the 11-year sunspot cycle.

In 1851, Bernhard Placidus Johann Nepomuk Bolzano's study of paradoxes was published, three years after his death.  In this work, he gives examples of one to one correspondences between elements of a set and its subset.

In 1852, Franz Unger put forth his theory of the common descent of plants.

In 1852, George Gabriel Stokes, exploring the blue light produced at the surface of a solution when it absorbed invisible ultraviolet light from the Sun, devised a method for artificially producing the phenomena and called the phenomena 'fluorescence.'

In 1852, Georges Newport observed the penetration of the vitelline membrane of a frog egg by sperm.
In 1853, Alexander Wood introduced the hypodermic syringe which was used as a morphine delivery system in the American Civil War.
In 1853, L.Teichmann discovered and named 'heme,' the non-protein, iron-bearing part of blood (Teichmann 1853). [revised 02/01/03]
In 1853, Florence Nightingale first recommended the regimen of cleanliness which dramatically reduced the death rate in hospitals.

In 1854, Rudolph Virchow published the idea that the mechanism of disease could only be found at the level of cellular chemistry.

In 1854, Helmholtz predicted the heat death of the Universe on the basis of thermodynamic theory.

In 1854, Georg Friedrich Bernard Riemann, in Ueber die Hypothesen, welche der Geometrie zu Grunde liegen, proposed another substitute for Euclid's fifth postulate representing elliptic space. He also said that "the empirical notions on which metrical determinations of space are founded, the notions of a solid body and a ray of light, cease to be valid for the infinitely small....  In a continuous manifold..., we must seek the ground of its metric relations outside it, in binding forces which act upon it" (Riemann, quoted in Cao 1997:372). 

In 1855, Wallace, in "On the law which has regulated the introduction of new species," also known as the 'Sarawak Law,' published the principle that species are always in proximity to an allied species which precedes it in the fossil record. He deduced this from evidence in the Malay Archipelago, "which is traversed near Celebes by a space of deep ocean [which] separates two widely distinct mammalian faunas" (Darwin 1872:335; Wallace 1855). [revised 02/01/03]

In 1855, Bernard maintained that the constancy of a body's internal environment was aided by secretions from tissues in all organs.

In 1855, Thomas Addison described a syndrome associated with the degeneration of the adrenal cortex, subsequently known as 'Addison's Disease.'

In 1855, David Alter described the spectrums of hydrogen and other gases. 
In 1855, John Snow, investigating London's piped water supply, showed graphically that cholera could be transmitted by water from a particular pump.
Between 1855 and 1860, Stanislao Cannizzaro showed that common gases like hydrogen exist as molecules and drew up a "table of atomic and molecular weights based on the the atomic weight of hydrogen as the fundamental unit of mass....  He also coined the name 'hydroxyl' for the OH radical" (Gribbin 2000:67).

In 1855, Julius Plücker drove an electric current through a vacuum tube, producing a glow of light.
In 1855, Herbert Spencer began publishing a projected ten volume work concerning the principles of synthetic philosophy, in which evolution was invoked as a universal principle that involved progress through stages toward greater complexity.

In 1856, fossils identified as an early variant of Homo sapiens were found in Neanderthal.

In 1856, William Ferrel published Essay on the Winds and Currents of the Ocean.

In 1856, Ludwig developed perfusion techniques which kept animal organs alive after their removal from the body.

In 1856, W. Thomson, in "Dynamical Illustrations of the Magnetic and Heliocoidal Rotary Effects of Transparent Bodies on Polarized Light," explained the Faraday effect in terms of the rotation of molecules, i.e., William John Macquorn Rankine's hypothesis, and argued that, "from any galvanic current, there extends a moving spiral that coils about the line of magnetic force passing through the center of the axis of the current" (Buchwald 1976:384).  A few years later, in a lecture, "Atmospheric Electricity," he stated what he took to be proved, namely, "that electricity in motion IS heat; and that a certain alignment of axes of revolution in this [vortical] motion IS magnetism" (Thomson 1860:224). [revised 02/01/03]

In 1856, Wilhelm Eduard Weber and Rudolph Herrmann Arndt Kohlrausch collaborated on the measurement of the ratio between the electrodynamic and electrostatic units of charge.  This was found to be 3.1074 x 108 meters per second, close to the speed of light.

In 1857, Pasteur demonstrated that lactic acid fermentation is carried out by living bacteria.

In 1857, Albert von Kolliker described what were later named 'mitochondria' in the nucleus of muscle cells.[added 02/01/03]

In 1857, Clausius, in "Ueber die Art der Bewegung, welche wir Wärme nennen," derived a much improved formula connecting pressure and volume, 3/2 pV=nmu2/2 and ascribed rotational, vibratory, and translational motion to gas molecules.  "By supposing that translational velocities would vary among the molecules, Clausius offered an explanation for the evaporation of a liquid.  [He also] presented the first physical argument in support of Avogadro's hypothesis that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules" (Daub 1976:306-307).

In 1857, Cyrus Field made his first attempt at laying a trans-Atlantic telegraph cable.  In 1866, his fourth attempt was successful.

In 1858, Darwin's friends, including Lyell, arranged for the simultaneous announcement of Wallace's and Darwin's idea of natural selection.

In 1858, Friedrich August Kekulé von Stradonitz suggested that carbon atoms are formed in chains.

In 1858, Helmholtz, in Handbuch der physiologischen Optik, Volume II, amended Young's trichromatic color theory, proposing that any wavelength of light, regardless of how strongly it excites one set of receptors, will always excite the other two sets, thus accounting for the lower saturation of spectral colors as compared to the physiological primaries.  This theory was henceforth known as the Young-Helmholtz theory.

In 1858, Arthur Cayley, in Memoir on the theory of matrices, defined a 'matrix,' showed that the "coefficient arrays studied earlier for quadratic forms and for linear transformations are special cases of his general concept[, and] gave an explicit construction of the inverse of a matrix in terms of the determinant of the matrix" (O'Connor and Robertson 1996:4). 

In 1858, August Ferdinand Möbius, while investigating the properties of one-sided surfaces, invented the so-called 'Möbius strip.'

In 1859, Darwin in On the Origin of Species by Means of Natural Selection or the Preservation of Favored Races in the Struggle for Life, asserted all life had a common ancestor and that the origin of species was natural selection acting on variants within a population and yielding differential reproduction of the most adapted, and that this was comparable to the artificial selection practiced by plant and animal breeders.  Until Darwin, the conception of mutation was confused by its application to what Linnaeus identified as species, which were actually aggregates of species.  Subsequently, leading anatomists, like Ernst Heinrich Haeckel, reoriented their work to the tracing of evolutionary relationships among animal groups.  Darwin was an experienced geologist--in fact, he served as the secretary of the Geological Society from 1838 to 1841, and a large part of On the Origin of Species is devoted to describing geological evidence, from which he drew illustrations of "what was then a generally admitted proposition: that the forms of organic life which had succeeded each other on the earth were progressive in character....  But uniformitarianism as an attitude toward the course of nature could not be carried to its logical conclusion in a theory of organic evolution until a formulation sufficiently scientific to be compelling could attack the idea of a governing Providence in its last refuge, the creation of new species" (Gillispie 1951:217-218).
In 1859, cocaine was isolated and patented by Merck three years later.

In 1859, Kolbe synthesized salicylic acid.

In 1859, Robert Wilhelm Bunsen discovered that each element produces its own characteristic set of lines in the spectrum.  Thus was 'spectography' invented, which, with photography, enabled the subsequent advances in astronomy.  Gustav Robert Kirchhoff followed up Bunsen's discovery and "made the first identification of the presence of any element outside the Earth when he found the characteristic sodium lines in the spectrum of light from the Sun" (Gribbin and Gribbin 2000:57).

In 1859, Kirchhoff proved a theorem about blackbody radiation, namely, the energy emitted E depends only on the temperature T and the frequency v of the emitted energy, i.e., E = J(T,v) and is independent of the nature of the body.  The correct formula for the function J, despite the efforts of Josef Stefan, Ludwig Boltzmann, John William Strutt, and Wilhelm Carl Werner Otto Fritz Franz Wien, was not found until Max Karl Ernst Ludwig Planck did so in 1900. 
In 1859, Riemann, in Beweis des Satzes, dass eine einwerthigemehr als 2nfach periodische Function von n Verónderlichen unmöglich ist, generalized to n dimensions Gauss's differential geometry.  This created the tools for the mathematical expression of the general theory of relativity.

In 1860, Pierre Eugöne Marcelin Berthelot, in Chimie organique fondeé sur la synthöse, described the synthesis of several carbon compounds.
In 1860, Bunsen and Kirchhoff, in Chemische Analyse durch Spektralbeobachtungen, recounted their discovery of cesium and rubium and explained the Fraunhofer lines in the solar spectrum as being dark absorption lines which are created by cooler gaseous clouds absorbing energy from the Sun.  Bunsen also explained the action of geysers.  Kirchhoff formulated two laws concerning electricity: At any instant the sum of the voltages around any loop is zero and at any node the sum of the arriving and departing currents is equal.

In 1860, Gustav Theodor Fechner, in Elementen der Psychophysik, attempted to explain how the psychical and the physical are two aspects of one reality. He formulated the rule that, within limits, the intensity of a sensation increases as the logarithm of the stimulus. Sigmund "Freud took from Fechner the concept of mental energy, the 'topographical' concept of the mind, the principle of pleasure-unpleasure, the principle of constancy, and the principle of repetition" (Ellenberger 1970:218).

In 1860, Maxwell, in "Illustrations of the dynamical theory of gases," showed that viscosity is independent of density, or pressure.

In 1860, Joseph Wilson Swan made an incandescent lamp using a carbon filament.

In 1860, de Morgan, in Syllabus of a Proposed System of Logic [?], invented a logic of relations, built on the idea of subject and predicate, e.g., the notation X..LY represents the statement that X is one of the objects in the relation of L to Y.

By 1861, Paul Broca was able to further isolate the language function and showed that a lesion in the left cortical lobe causes the loss of speech, or 'aphasia,' thus demonstrating an asymmetry that Gall had not suspected (Broca 1861). [revised 02/01/03]

In 1861, Ignaz Philipp Semmelweis published his deduction that childbirth fever was transmitted on the hands of doctors during their examinations.

In 1861, William Crookes, using a spectroscope, announced a new element, 'thallium.'

In 1861, Maxwell, in "On Physical Lines of Force," announced his discovery that some of the properties of the vibrations in the magnetic medium are identical with those of light: "The velocity of transverse undulations in our hypothetical medium...agrees so exactly with the velocity of light...that we can scarcely avoid the inference that light consists in the transverse undulations of the the same medium which is the cause of electric and magnetic phenomena" (Maxwell 1861:500).

In 1861, Anders Jonas Ångström, using a spectroscope, confirmed the presence of hydrogen in the Sun.

As early as 1861, Karl Wilhelm Theodor Weierstrass, in lectures, showed that "a function which is continuous throughout an interval need not be derivative at any point in this interval....  Inasmuch as it was apparent to Weierstrass that intuition could not be trusted, he sought to make the bases of his analysis as rigorous and formal as possible....  In order to [accomplish this, he] wished to establish the calculus (and the theory of functions) upon the concept of number alone, thus separating it completely from geometry" (Boyer 1949:284-285).  Weierstrass' lectures were published, as Die Elemente der Arithmetik, by one of his students in 1872. 

In 1862, Henry Walter Bates said that in 'lepidoptera,' a class of butterflies and moths, mimicry in appearance of unpalatable species by palatable species suggests that the mimics enjoy protection from predation.

In 1862, Pasteur published the 'germ theory:': Infection is caused by self-replicating microorganisms, and that attenuated viral cultures granted immunity.  These beneficent antigens he named 'vaccines' in honor of Jenner and his vaccinia virus.
[Pasteur was a proponent of 'vitalism,' which "accepted the word 'life' as a substitute for specific chemical information" (Kornberg 1989:34); hence, fermentation was "a physiological process, inseparably connected with the vital act of a microorganism known as the 'fungus of fermentation'" (Sönderbaum 1929:1).  "The various vitalist theories, more or less scientific in appearance, all presuppose the existence of a teleonomic principle [or goal or end], of a special guiding force present in living matter, absent in inanimate matter" (Monod 1969:5).  Thus there is no reason that physics should illuminate the processes of life since they are essentially different and not reducible to one another.]
In 1862, Béguyer de Chancourtois proposed a pattern of twenty-four elements on a cylindrical table with periodicity of properties.

In 1862, Julius von Sachs produced experimental evidence that starch was a product of photosynthesis.

In 1862, W. Thomson, in "On the Age of the Sun's Heat," deduced a maximum limit for the age of the Sun and said that the Earth "must have solidified from its primordial molten state not less than 20 million and not more than 400 million years ago.  These limits were rigorous deductions from Fourier laws applied to the case of a molten sphere cooling through emission of radiant heat" (Buchwald 1976:383).

In 1863, Helmholtz, in Die Lehre den Tonempfindungen als physiologische Grundlage für die Theorie der Musik, formulated a theory of hearing in which the transverse fibers of the basilar membrane in the cochlea act as resonators.

By 1863, William Huggins had collected several stellar spectra which showed that stars consisted in the same gases as the Sun.

In 1863, Thomas Henry Huxley, in Evidence of Man's Place in Nature, expounded Darwin's theory of evolution. [added 02/01/03]

In 1864, Felix Hoppe-Seyler named the colorless, proteinaceous part of blood 'globin;' thus, haemoglobin (Hoppe-Seyler 1864).  His spectroscopic reports led Stokes to describe, on the basis of more spectroscopic observations, the physiological function of blood as illusrated by its repeated reduction and oxidation (Stokes 1864). [revised 02/01/03]
In 1864, John Alexander Reina Newlands prepared the first two-dimensional periodic table of the elements.  This was arranged in the order of atomic weights and remarked the 'law of octaves,' i.e., that every eighth element known at that time had similar properties.  In the same year, William Odling published a chart with fifty-seven regions including some gaps.  Still in the same year, Julius Lothar Meyer showed that the ability of elements to form compounds with one another varied periodically with atomic weight.

In 1865, O. F. C. Deiters, in Untersuchungen über Gehirn und Rückenmark des Menschen und der Säugetiere, proposed the image of the nerve cell which is accepted today: cell body with its nucleus, multiple, branching dendrites, and a single axon. [revised 02/01/03]
In 1865, Bernard observed, in Introduction à l'étude de la médecine expérimentale, that the internal environment was balanced or self-correcting, that disease states are often extreme manifestations of normal processes, and that, between living matter and the physical world, the difference is in the degree of complexity, which is greater in living systems (Bernard 1865:111-117).  He was explicit in his attack on biological vitalism.
In 1865, Lister, using carbolic acid as antiseptic and sterilizing his instrument, proved the efficacy of antiseptic surgery.
In 1865, Stradonitz devised a ring model for the structure of benzene.
In 1865, Maxwell, in "A Dynamical Theory of the Electromagnetic Field," concluded that the known electric, magnetic, and electromagnetic phenomena are explained by mathematical equations restating Coulomb's law, Ampère's conjecture, Faraday's law of induction, with the addition of the inversion of Faraday's law, namely, that a magnetic field could be generated by a changing electric field, and the dynamical basis of the theory is the transmission of energy in the required medium, an electromagnetic field-required in order to avoid 'action at a distance.'  "The mechanical analogy for [this] field is explicated in terms of energy relations, rather than the pictorial mechanical model contrived in 'On the Physical Lines of Force'" (Harman 1998:116).
In 1865, Clausius, in "Ueber verschiedene für die Anwendung bequeme Formen der Hauptgleichungen der mechanischen Wärmetheorie," reformulated "the fundamental laws of the Universe which correspond to the the two fundamental theorems of the mechanical theory of heat.  1. The energy of the universe is constant.  2. The entropy of the universe tends to a maximum" (Clausius 1865:365).
In 1865, the first rapid and sustained trans-Atlantic telegraphic cable was laid using a mirror-galvanometer, an instrument designed by W. Thomson, in order that small voltages could be detected (Buchwald 1976:387).

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