PRELUDE TO MODERN SCIENCE--THE EIGHTEENTH CENTURY
When the eighteenth century opened science had begun to make men think,
and the works of the great scientists had changed the trend of thought
on all sides. Liberty of conscience, of worship, and of opportunity
were demanded, as well as representative government, economic freedom,
and individual equality before the law. Men wanted to be free agents.
The philosophical writings of Berkeley, Locke, Hume, Spinoza, Voltaire,
Rousseau, and others supplemented the books of the scientists and
promoted rational thinking. Syllogistic reasoning displaced the
practice of accepting beliefs upon authority. This change in public
thought reacted most favorably upon science.
Gottfried Wilhelm Leibnitz (1646-1716) conceived matter as a plurality
of simple forces. Many kinds of matter, he said, exist. There is no
single natural force, but an infinite number. Each force is represented
by some individual substance. Force is indivisible, immaterial, and
unextended. Simple forces he called essential forms, units, atoms, or
monads. The monads are not mathematical points, nor physical points.
Real points are metaphysical. In other words, Leibnitz created a
philosophy of eternal force atoms.
The Greeks were taught by Leucippus, Empedocles and Anaxagoras that
matter is formed of atoms. Space is infinite; atoms are indivisible.
Atoms are in a continuous state of activity. Atoms constitute worlds
and planets. Falling through space they give rise to eddying motions
by mutual impact. Many philosophers rejected these views. Throughout
the ages, however, they were learned by students and when Leibnitz
advanced his new atomic theory, the world was ready to consider it.
The Leibnitzian monads were like Plato's ideas--eternal purposes.
Aristotle held that monads are absolute, indivisible beings. Leibnitz
suggested that each monad is in process of evolution and realizes its
nature through inner necessity. It is not determined from without. Each
form of matter existed in germ in an embryo. Nothing in a monad can be
lost, and future stages are predetermined in the earlier stages. Each
monad is charged with the past and big with the future. The biologists
at this period generally accepted this incasement theory. Caspar F.
Wolff suggested, in 1759, that there is an epigenesis or a progressive
evolution and differentiation of organs from a homogeneous primitive
germ. This view did not meet with approval until Darwin published his
great discoveries in the middle of the last century.
The history of the atomic theories furnishes a clear illustration of
the long period of preparation that great scientific ideas must pass
through before they are united by a generalizing genius of exceptional
capacity and launched in the form of a new theory.
Modern mathematical science grew out of the analytical geometry
of Descartes. He showed that the true method for the discovery of
scientific facts was to accept nothing as true which was clearly not
recognizable as true. All assumptions should be proved. Each difficulty
should be separately studied. No intermediate steps should be skipped,
and details should be methodically enumerated. Thoughts must be guided
in an orderly manner, beginning with the simplest characteristics of
an object and proceeding in a logical sequence to the most complicated
aspects of each subject. Descartes carried out his own rules in
his work. His improvements in the differential calculus, and those
in the integral calculus made by Cavalieri, and in the calculus
of probabilities by Pascal and Fermat, furnished scientists with
instruments capable of solving almost every physical problem met with
in their investigations.
One of the first results of the new analytical methods was the
establishment of the science of optics.
Newton demonstrated that white light is composed of rays of various
colors, and that the color reflected by any object is due to the
ability of the object to reflect certain rays while absorbing the rest.
The Dutch physicist, Huygens, championed the undulatory or wave theory
of light. Refraction was explained by both Newton and Huygens, and the
latter, while studying the double refraction of crystals of Iceland
spar, discovered the phenomena of polarization.
Boyle's chemical discoveries led to much research in chemistry. Black,
Bergman and Van Helmont investigated the properties of carbonic acid
gas.
Joseph Black treated limestone with acid and collected the gas evolved
in a Hales pneumatic trough. He weighed the gas and the remainder of
the limestone, finding that what the limestone lost was equivalent to
the weight of the gas. He then reversed the process and succeeded in
making chalk from a solution of lime. This simple experiment paved the
way for chemical analysis and syntheses which have added profoundly to
our knowledge of the composition of matter.
Bergman tested Black's gas with litmus and found it gave an acid
reaction and in 1779 Lavoisier demonstrated that it consisted of carbon
and oxygen.
Priestley and Cavendish, both English chemists, then took up this
study. Cavendish treated iron, tin, zinc, and other metals with
sulphuric acid and discovered a new gas which he termed hydrogen.
Rutherford discovered nitrogen in 1772 and Priestley isolated nitric
oxide, and in 1774 discovered oxygen. In the course of his experiment
Priestley also discovered ammonia, sulphur dioxide and other chemicals.
His greatest achievements, however, were the isolation and recognition
of oxygen, and the discovery of the composition of water. Following up
these discoveries, he noted that the air is not a simple elementary
substance, but a mixture of nitrogen and oxygen with several impure
gases. The work of this great chemist became as fruitful in the
chemical field as that of Newton in physics, astronomy, and mathematics.
Carl Wilhelm Scheele, a Swede, carried out many experiments which
resulted in the discovery of tartaric acid, the decomposition of silver
chloride by light, magnesium nitrate, magnesia, microcosmic salt, and
sulphureted hydrogen, chlorine, hydrofluoric, and other inorganic
acids. He also discovered the following organic acids: lactic, gallic,
pyrogallic, oxalic, citric, malic, mucic and uric. He isolated
glycerin and sugar of milk and determined the nature of hydrocyanic
acid, borax, plumbago, Prussian blue, and other chemicals. He invented
many new chemical and laboratory processes. Scheele was an apothecary's
assistant and lived in poverty. But although his experiments were
conducted under disadvantageous circumstances his discoveries ranked
him as the greatest chemist of his time and one of the greatest
chemical experimenters of all time.
Cavendish established the proportions of the constituents of air,
demonstrated the nature of water and its volumetric composition. The
character of the experiments conducted by Cavendish, his elegant
methods of weighing, measuring and calculating have caused him to
be looked upon as the founder of systematic chemistry. He was more
scientific in his methods than the brilliant Lavoisier, and much more
learned and philosophical than the practical Scheele.
While the chemists were making these great advances there were
important developments in physical science. Benjamin Franklin
(1706-1790), the first American scientist to acquire world-wide
fame, announced that lightning was an electrical phenomenon. In
1752 he showed by his famous kite experiments that atmospheric and
machine-generated electric charges are of a like nature.
Franklin suggested to Cavendish certain electrical experiments with
a view to studying the electric force between two charges. These
experiments led Cavendish to the discovery of the law of electric
attraction between charged bodies. Franklin subsequently discovered the
law of conservation of an electric charge.
Charles Augustin Coulomb (1736-1806) rendered great service to
electrical experimentation. He resurveyed the experiments of Cavendish,
Priestley, and other pioneer electricians, and established a theory of
molecular magnetization which provided a working formula to explain
electrical currents and magnetic fields.
Simeon Denis Poisson (1781-1840) discovered the law of induced
magnetism which bears his name.
Luigi Galvani (1737-1798) observed that the limbs of a frog are
convulsed whenever they are connected up through the nerves and muscles
with a metallic arc formed from more than one metal. He thought the
convulsions were due to a peculiar fluid which he called galvanism, or
animal electricity.
Another Italian, Alessandro Volta (1745-1827) discovered and explained
the theory of the voltaic pile.
Nicholson and Carlisle discovered frictional electricity while William
Cruickshank showed that a voltaic current decomposes solutions of
metallic salts. William Hyde Wollaston used Cruickshank's discovery
to prove that frictional and voltaic electric currents are identical.
Humphry Davy (1778-1829) in 1807 established a new voltaic theory
which combined the chemical and contact theories previously held, and
showed that electrical and chemical attractions are produced by similar
causes. Chemical affinity he found to be an essentially electrical
phenomenon.
Francis Hawksbee, in 1705, communicated to the Royal Society a
monograph which showed that when common air is passed over mercury in
a well-exhausted receiver an electric light is produced. This was
the first demonstration of the availability of electricity for the
production of light.
Dufay (1699-1739) described positive and negative electric currents.
Watson determined, for the Royal Society, the velocity of an electric
current and found it practically instantaneous.
These, and numerous lesser, discoveries did for electricity what
the chemical discoveries of Priestley, Cavendish, Scheele, Boyle,
Lavoisier, and others had done for chemistry.
The numerous voyages of discovery in the eighteenth century helped to
develop the geographical sciences. Special expeditions were fitted out
for the acquirement of geographical knowledge without any thought of
trading profits. The Jesuits carried out a valuable survey of China and
Mongolia early in the century. A Danish scientific expedition studied
Arabia, the results of which were published by Niebuhr in 1772. James
Bruce visited Abyssinia with the view of solving the ancient problem
of the source of the Nile. Mungo Park studied the course of the Niger.
Captain James Cook led a scientific expedition to Tahiti with the
object of making astronomical observations. This resulted in one of
the greatest and most valuable voyages of discovery in history. Cook
determined the westernmost point of America in 1778 and his accounts
of Bering Sea and Alaska revived interest in the Polar seas, which
resulted in numerous Arctic and Antarctic expeditions yielding rich
scientific returns.
The Hudson's Bay Company sent out many investigators to determine the
characteristics and resources of Arctic America. The Russians did the
same for their own northern lands.
These activities of geographical investigators led to improved methods
of navigation, nautical surveying, sounding and shipbuilding, besides
supplying an enormous amount of scientific data.
The British naval authorities pointed out to King Charles II the need
for correct nautical tables. Flamsteed, one of the leading astronomers
of the day, was appointed Astronomer Royal in 1675, with the definite
object of producing a new catalogue of star positions, tide tables, and
other nautical data. He immediately founded the Greenwich observatory,
which has supplied the world with data for the navigator.
Bradley, a successor of Flamsteed at Greenwich, made many important
astronomical discoveries while carrying on the star maps. He discovered
the aberration of light and the mutation of the earth's axis.
Locaille studied the parallax of the sun and made numerous stellar
observations at the Cape of Good Hope in 1751. He located the positions
of 10,000 stars in the southern hemisphere.
Measurements were made in Peru, Lapland, and elsewhere to discover
data regarding the earth's curvature. Pendulum observations to detect
variations of gravity were made in many countries. Maskelyne, the
astronomer royal, made observations on the transit of Venus at St.
Helena in 1761. On this expedition he perfected the method of finding
longitude at sea by lunar distances.
Sir William Herschel discovered the planet Uranus in 1781, and
subsequently found its satellites. Many star groups, double stars and
nebulæ were discovered by him and he found that the solar system is
traveling through space in the direction of a point in or near the
constellation of Hercules.
Greenwich observatory was publishing at the end of the eighteenth
century the Nautical Almanac, and annual reports on star and
meteorological observations as well as important astronomical
monographs. Similar publications were founded in the next century in
France, Germany, and Italy.
The discoveries in mathematics during the eighteenth century included
the differential, integral, and other forms of the calculus,
differential equations, and various formulæ for dynamics, mechanics,
and physical and astronomical calculations. Euler, Lagrange, Laplace,
D'Alembert, and Carnot were prominent mathematical investigators.
Heat in earlier times had been regarded as an imponderable substance
called caloric which was supposed to be emitted by hot and absorbed
by cold bodies. Thus the expansion of mercury was explained by the
addition of caloric and not by the increase of distance between
the molecules. Francis Bacon and the Scotch chemist Black did the
preliminary work which enabled Count Rumford finally to establish
the true theory of heat. Watt and Newcomen were attracted by these
studies and reduced their theories to practice in the steam engine.
Black described specific and latent heat and invented, and used, the
calorimeter bearing his name.
Hall invented an achromatic lens for telescopes in 1733, and Dollond,
another English optician, improved achromatic lenses and made, in 1758,
achromatic telescope objectives. The lenses were primarily designed
for astronomical telescopes, but they were also applied to microscopes
and other scientific instruments, resulting in improvements in our
knowledge of light.
The voyages of discovery, in this century, encouraged study of zoölogy
and natural history subjects generally, including mineralogy and
geology.
Hooke, Ray, and Woodward made collections of rocks and fossils in
England and advanced hypotheses to explain their origins. Lazzaro
Moro suggested that fossils must have been deposited in rocks when
they were being formed. He also distinguished rock formations by the
characteristic fossils found in them. Hutton and Smith then made
scientific studies of English rocks, fossils, and earth sculpture, and
prepared the materials for the subsequent brilliant discoveries of
Lyell.
The first governmental school of mines was established in Freiberg,
Saxony, in 1775. This institution, and others which were afterward
established in different countries, led to an intensive study of the
geological and metallurgical sciences, which eventuated in great
advances during the nineteenth century.
Aristotle and Theophrastus in early times, Gesner in the sixteenth
century, Ray, Grew, Malpighi and Willughby in the seventeenth century,
had been the writers of the principal textbooks on zoölogy. Buffon
(1707-1785) and Linnæus (1707-1778) were the founders of modern natural
history in the eighteenth century. Buffon described species, while
Linnæus classified them. Linnæus named _Homo sapiens_ as a distinct
species in the order of primates which includes apes, lemurs, and bats,
and fixed man's place in nature.
The medical sciences were revolutionized by the researches of
Edward Jenner. He applied the scientific methods of the chemists,
mathematicians, and astronomers to medicine and through accurate
observation, skillful experimentation, careful generalization, and
thorough verification, founded preventive medicine. His discovery of
vaccination as a preventive for smallpox, communicated to the Royal
Society in a very interesting paper in 1798, was the pioneer of the
many brilliant advances of our day.
The Freiberg School of Mines, the Woolwich Observatory, the School
of Civil Engineering in Paris (1747), the Universities of Göttingen
(1737), Bonn (1777), Brussels (1781), Yale (1701) and Princeton (1746)
were founded in this century.
Modern industrialism began in the final part of this century.
The invention of the steam engine by Watt resulted in giving the
greatest impulse to material civilization the world ever experienced.
This invention was the direct result of the experimental work of
Boyle, Newton, Black, Cavendish, Davy, Priestley, and Lavoisier. It
illustrates how the scientific discoveries of one generation furnish
the data for the advancement of knowledge by the next generation and
how a single invention may change the whole aspect of life, giving
employment for vast numbers of people, developing settlement in foreign
lands, starting new industries, and extending the fields of commerce.
The history of the development of the steam engine from the results of
a few basic physical researches by British scientists forms one of the
grandest stories in the history of science.
The new aspect assumed by the world as a result of the great scientific
discoveries and the increases in industry and commerce which followed
them seemed strange to the people who were unused to rapid progress.
There was a disturbed feeling akin to fear abroad while the new ideas
were being popularized and disseminated throughout the world. The
movement in favor of enlightenment was strongest in France because of
the social, political, and religious oppression of the people. It ended
in the French Revolution, which strengthened the respect for reason and
human rights throughout the world.