CHAPTER VIII

SCIENCE IN THE SEVENTEENTH CENTURY

The wonderful advances made in the mathematical, physical, and astronomical sciences, and the invention of many new scientific instruments, together with the publication of improved textbooks and scientific tables, like those mentioned in the preceding chapter, stimulated interest in other fields of science at the beginning of the seventeenth century.

Medicine, which failed to advance with the astronomical and physical sciences, began to improve. The Moors had established great medical schools in Spain, but their teachings were based upon the principles enunciated by Hippocrates and the Greek schools.

Modern medicine was started upon a firm basis by John Harvey (1578-1657). Hippocrates taught that the blood was one of the principal parts of the body--one of the four great "humors." Its movements, however, had never been investigated until Harvey began to study the functions of the arterial system by the dissection of animals. The arteries had been considered as merely air tubes. This was due to the fact that they were studied only in post-mortem examinations when they were empty. The anatomists of the sixteenth century failed to grasp their importance.

Harvey, who was a penetrating observer, had studied in several continental universities as well as in England, and having an original mind he determined to test the medical theories which he had been taught. His discoveries of the functions of the heart, the arteries, and the veins were epochal. He did his work so well and made such simple, yet telling, demonstrations that he had less difficulty than his predecessors in getting his teachings accepted. He was soon recognized as the peer of Hippocrates and Galen.

Harvey died without actually seeing the blood coursing from the arteries into the veins, but four years after his death Marcello Malpighi (1628-1694) exhibited microscopically the passage of blood corpuscles through the minute vessels in the lung of a turtle, on their way from the heart through the arteries into the veins and returning to the heart. The blood circulation was demonstrated at a subsequent date by applying a microscope to the web of a frog's foot. With low-powered lenses a good view is obtainable in this manner.

Many other important discoveries were made by Harvey, particularly in embryology. He demonstrated that the embryo chicken is formed by gradual development and processes of differentiation and not, as had previously been believed, from a minute perfect chicken.

Microbes were discovered in 1683 by Antonius von Leeuwenhoek (1632-1723), when he was examining some scrapings from his teeth. He saw for the first time the long and short rods of bacilli and bacteria, the spirillum and the micrococci. He tried means for destroying them and met with a fair degree of success with a gargle composed of a mixture of vinegar and hot coffee. This experiment was one of the early anticipations of antiseptic surgery, which was invented by Lister in the nineteenth century.

A French surgeon, Ambroise Paré (1517-1590) was a pioneer in the treatment of wounds. The old method was to use boiling oil. He found that by simply cleaning and bandaging wounds he could get better and quicker results than with hot oil, which was a very painful treatment. Paré used ligaments in stopping hemorrhages, improved the surgery in harelip and hernia operations and for suprapubic lithotomy. He learned the principles of these operations from Peter Franco (1505-1570), an itinerant surgeon, who had much skill in operations for kidney and bladder troubles.

Franz de la Boë (1614-1672), a professor in the university of Leyden, who is best known under the name of Sylvius, the discoverer of the brain fissure of Sylvius, founded a new school of chemical medicine. Van Helmont suggested to him the possibility of the stomach being the seat of many common disorders. When this was investigated, many experiments were made with new medicines. The success of these experiments led to a great reform in medical practice. Thomas Willis (1622-1675), an English physician, completed the development of the treatments suggested by Van Helmont and Sylvius as a result of their studies of the works of Harvey.

Another great English medical genius arose to establish the practice of medicine on a scientific basis. Thomas Sydenham (1624-1689) founded a school of medicine in accordance with these three principles: (1) Accurate descriptions of the courses of diseases, (2) following a fixed method of treatment in each disease, (3) searching for specific remedies for each diseased condition.

The results of these teachings were very pronounced. Before Sydenham's time, the only drug used in medicine was an extract of cinchona. The Dutchmen above named and Sydenham discovered many active medicinal substances. Sydenham's principal discovery in materia medica was that of the properties of laudanum.

William Gilbert, court physician to Queen Elizabeth of England, while Galileo and Stevin were developing the laws of gravitation and hydrodynamics, undertook the investigation of the laws of terrestrial magnetism and chemistry. His researches in chemistry were extensive and valuable. His fame, however, was perpetuated by his study of magnetism and electricity. He found that the earth is a vast magnet with north and south poles. His remarkable textbook on magnetism covered many of the fundamental facts known to-day. He noted the distinction between magnetism and electricity, described electrical charges, the principles of conductivity and methods for magnetizing iron. Galileo wrote of him: "I extremely admire and envy this author."

The mercurial barometer and its laws were discovered by Evangelista Torricelli (1608-1647) a student of Galileo. By means of his barometer, Torricelli was able to make great advances in knowledge relating to the physics of the air and to gas pressures, and he investigated the principles of hydraulics. The microscope, telescope, sextant and other instruments were greatly improved by him, and his mathematical work ranks only second to his contributions to experimental science.

The Torricellian tube, used as a barometer, was a means of creating a vacuum, which was formed at the top of the column of mercury. Pascal, the French mathematician, took up the study of the physics of the vacuum and published an important work on his own experiments. These and other experiments made by European scientists prepared the ground for, and suggested, the investigations of gases and vacua by Boyle, Mariotte, and others which finally resulted in the invention of the steam engine and many other modern machines.

Robert Boyle (1627-1691) published at Oxford in 1660 a book which distinguished between chemical compounds and chemical mixtures. He adopted the use of the term gas, which was first proposed by Van Helmont, and made some valuable studies on the physics of boiling and freezing. The oxidation of metals, the results of calcination, and of the fusing of metals and alloys, calculation of the atmospheric pressure, a study of colors as affected by light rays, and investigations in electricity were among the scientific works carried out by this great experimenter. But his fame rests mainly upon the results of his researches on gases.

Boyle began life as an alchemist and died a well-trained chemist.

Edme Mariotte, a French contemporary of Boyle's, carried out similar experiments and assisted in formulating the physical laws of gases bearing the names of Boyle and Mariotte.

A German physicist, Otto von Guericke (1602-1686), also followed up Boyle's work and invented a new form of air pump. He also carried on important experiments in electricity.

Gilbert, Harvey, Van Helmont, Torricelli, Boyle, Mariotte, and other similar pioneers in scientific methods not only invented numerous valuable instruments and wrote suggestive textbooks, but advanced scientific learning and the love of it by their delightful accounts of their experiments.

Modern education started with these men. Before this period there had been a sterile age in which the fundamental purpose of education was only to teach men how to protect the soul and to serve God. This humanistic principle, however, failed to advance knowledge of the laws of nature, and the researches of the scientists gradually caused a strong reaction against it. This in turn resulted in further advances being made, not only in the sciences, but in all departments of learning. The way was paved for the era of naturalism, developed by Hobbes, Locke, Descartes, Voltaire, Kant, Rousseau, and others. Naturalism aimed at explaining all phenomena in the simplest terms, and correlating all things by universal principles. It has received a great impetus in modern times from the Darwinian theory of evolution.

The great scientific discoveries of the sixteenth and seventeenth centuries had other important educational effects. They led to professional specialization and the founding of scientific institutions, schools, and universities. The Lyncean Society of Scientists was founded in Italy in Galileo's time. It subsequently became, in 1657, the Accademia del Cimento.

The Royal Society of England was organized about 1645 and chartered in 1662. It did much valuable scientific work from its inception. It has assisted the foremost scientists in their work, directed scientific researches, and financed the printing of scientific records and the carrying out of foreign expeditions. Nearly all the leading countries in the world have formed institutions with similar aims.

The chemical discoveries of Boyle attracted widespread attention and led to investigations started with the view of discovering the constitution of matter. Hermann Boerhaave (1668-1738) of Leyden, took up the study of organic chemistry. Stephen Hales (1677-1761) did similar work in England. Both of these chemists invented valuable laboratory processes and instruments. Hales improved the pneumatic trough used for collecting gases.

Scientists were now furnished with the telescope, compass, sextant, microscope, barometer, thermometer, air pump, manometer, and other instruments so that cellular structures of plants, animals, and insects, the microbes and bacteria, the animalculæ found in water and in the sea, as well as the phenomena of the air, sky, and earth crust could now be studied by trained observers. The invention of these instruments caused workers to specialize more and more, and completely severed science from philosophy, of which it had been an appendage since the earliest times.

The microscopical investigations of Malpighi, Kircher, Leeuwenhoek, Grew, and Hooke opened up an immense field for research. They developed microscopical chemistry and anatomy, and changed the prevailing ideas regarding animal and vegetable tissues. The sciences of mineralogy, botany and entomology were benefited and the medical sciences were practically revolutionized. The first publications of the Royal Society show the widespread attention microscopical and telescopic studies were then receiving.

Francis Bacon (1561-1626), René Descartes (1596-1650) and Gottfried Leibnitz (1646-1716), in England, France, and Germany, respectively, lent powerful aid to the advance of science at this time.

Bacon's great learning enabled him effectively to describe scientific methods and to direct scientific criticism. He attracted general attention to scientific methods based on inductive processes.

Descartes, seeing that the world's best intellects had long been exercised with philosophy and metaphysics, without discovering anything with certainty, resolved to accept no beliefs upon the authority of any name or reputation. He would reach his own conclusions based upon the scrupulous examination of data. He hoped to solve the mysteries of nature by the aid of mathematics and geometry, and developed the Cartesian philosophy.

The mathematical works of Descartes are now better known than his general scientific ideas. He published in 1637 his "Discourses on Method" and on Geometry. In the last-named work, suggestions are given for the development of analytic methods. It has been said of his formulæ that they are even cleverer than himself. The general use of his analytic methods by other mathematicians resulted in the solution of many scientific problems that had been handed down for centuries as insoluble.

Descartes also advanced algebra. The application of the doctrine of curved lines to algebra greatly enlarged the scope of its usefulness. In making these innovations, Descartes introduced the methods and symbols of modern exponential notation. The English mathematician Wallis was also an important agent in the development of mathematical notation. He based his work on the Greek notation and that of Nicolas Chuquet (1484), J. Bürgi, Thomas Harriot (1631), Johann Hudde (1659), and others. Descartes was familiar with the writings of these scholars and, undoubtedly, was influenced by them.

Roberval, Fermat, and Pascal were contemporary mathematicians in France and left great names in the history of the mathematical sciences. They all made contributions which permanently enriched mathematics and made further progress in other sciences possible.

The geographical sciences now began to attract attention. The new scientific instruments made it possible to collect data in all parts of the world that was needed in unraveling scientific mysteries.

William Dampier (1653-1715) was one of the pioneers in scientific voyages of discovery. In voyages to the Orient and Australasia he collected much important data on zoölogy, botany, meteorology, the winds, tides, currents, and on fish and sea life. His book on winds became the first great standard work on meteorology.

The doctrine of spontaneous generation had long held sway in Europe. The Greeks entertained it and it was accepted as true in the time of Martin Luther. Francesco Redi (1626-1697), an Italian biologist, showed that when the flesh of dead animals is protected it remains fresh. The Abbé Spallanzani (1729-1799) carried Redi's theory further and showed that microbes and bacteria do not develop in concoctions which have been boiled and sealed. Here we note the beginning of antiseptic science.

Under the leadership of Bacon in England, Calvin in France, Luther in Germany, and Knox in Scotland, European thought was being stirred up while the great discoveries just related were being made. Just as Boyle's chemical discoveries caused the divorcing of chemistry from alchemy, and the naturalistic philosophy of the times led to the specialization of scientists and the breaking off of philosophy from science, so the intellectual awakening aroused by Bacon and his contemporaries led to the suppression of belief in witchcraft and to revolutionary ideas in religion and ethics.

Locke endeavored to base a "rational Christianity" on the ground of experience. Until his times, theology was tangled up with a maze of physical problems which dismayed even such intellects as those of Newton, Hume, and Locke.

Newton's researches were chiefly based upon mathematical and astronomical problems. While a student at Cambridge in 1660, he studied the works of Descartes, Kepler, Van Schooten, Barrow, and particularly those of the Greek and British mathematicians. The works of J. Wallis were very valuable to him. The "Arithmetic of Affinities" of Wallis drew his attention to astronomical problems and thus led to his great triumphs later on.

Newton's "Principia" has already been referred to as being one of the greatest works of the intellect ever produced.

The result of Newton's meditation upon the nature of the central force that keeps the planets in their courses was that he furnished a mathematical basis for Kepler's laws by proving that if the planets describe elliptical orbits about the sun, the force acting toward the sun, keeping them in revolution, must vary inversely as the square of the distance. On the revolution of the moon around the earth he found a practical confirmation of this law of gravitational attraction. He then took up the study of motion in general and showed that every particle of matter attracts every other particle in accordance with the same principle of inverse squares.

Botanical gardens were established in Padua in 1545, and not long after in Pisa, Leyden, Paris, and London. Much attention was devoted to medicinal plants, and numerous herbal books were published. Malpighi, Grew, and Camerarius (1665-1721) published works on botany and plant morphology. Ray and Linnæus (1707-1778) studied the classification of plants and compiled textbooks of descriptive botany.

Buffon (1707-1788) published his famous "Natural History of Animals" which did for zoölogy what the works of Linnæus did for botany.

Looking backward, we can now see that all scientific knowledge has been gained by the trial and error method and cumulative analyses of a multitude of observations. Progress is not made uniformly but in a recurrent, cyclic manner. Reactions follow advances, but in the end all goes forward.