|
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. |
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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). |
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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. |
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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. |
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In 1830, Robiquet and others discovered the hydrolytic splitting
of the glucoside, 'amygdalin.' |
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In 1830, Giovanni Battista Amici traced the growth of the
pollen tube down through the 'style' and into the ovule of the flower. |
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In 1830, Joseph Lister showed lenses which corrected for aberration. |
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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. |
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In 1830, Macedonio Melloni invented the thermocouple,
by which the transmission of heat by various substances can be measured. |
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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.' |
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In 1831, Brown discovered the cell nucleus in the course of a microscopic examination of orchids. [revised 02/01/03] |
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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] |
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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. |
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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. |
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In 1831, Berzelius proposed the name 'isomerism' for different compounds with same chemical composition, such as that discovered by Wöhler. |
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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. |
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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. |
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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). |
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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. |
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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.' |
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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). |
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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). |
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In 1833, Gauss invented the electric telegraph. |
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In 1833, Charles Wheatstone invented the 'stereoscope,' revealing the dependence of visual depth perception upon binocular double vision. |
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In 1834, Berzelius, in Annalen der physikalisches Chemie,
reported finding organic matter, humic acid, in a meteorite. Such
meteorites are called 'carbonaceous chondrites.' |
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In 1834, Anselm Payen and Jean-François Persoz isolated
'diastase' from barley malt and postulated the importance of enzymes in
biology. |
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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). |
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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. |
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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. |
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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. |
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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. |
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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. |
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In 1836, Theodor Schwann reported the action of 'pepsin' and
described its properties. |
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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). |
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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) |
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In 1837, René Dutrochet observed that chlorophyll is necessary for photosynthesis. |
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In 1837, Hugo von Mohl described 'chloroplasts' as discrete
bodies within the cells of green plants. |
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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). |
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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). |
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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. |
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In 1838, Mattias Jakob Schleiden put forward the theory that
plant tissues are composed of cells, and recognized the significance of
the nucleus. |
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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. |
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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] |
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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. |
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In 1838, Gerardus Johannes Mulder published Berzelius'
term 'protein.' |
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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. |
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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:). |
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In 1839, Mohl described the appearance of the cell plate between
the daughter cells during cell division, or 'mitosis.' |
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In 1839, Johann Schoenlein, using a microscope, discovered
a microbial parasite of humans, Trichophyton schoenleinii, which
causes ringworm of the scalp. |
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In 1839, Christian Swann discovered the existence of
ozone. |
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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. |
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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. |
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In 1840, T. L. Hünefel , in Der Chemismus in der thierischen Organization, reported his observation
of crystals in the blood . [revised 02/01/03] |
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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. |
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In 1840, Louis Agassiz published a demonstration of
the existence of a glacial epoch in the temperate zones. |
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In 1840, Christian Friedrich Schönbein isolated 'ozone,'
naming it from the Greek word ozein, to smell. |
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In 1840, Berzelius suggested the name 'allotropy' for the occurence different forms of the same element. |
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In 1841, Albrecht von Kölliker showed that spermatozoa are
sex cells which arise by a transformation of cells in the testes. |
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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. |
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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). |
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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. |
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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). |
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In 1843, Justus von Liebig speculated that organic acids, such as malic, tartaric, and oxalic, are intermediates in a plant's production of carbohydrates. |