The sciences advanced in logical progression through modern history: mathematics and physics in the seventeenth century, chemistry in the eighteenth, biology in the nineteenth, psychology in the twentieth.
The great name in the physics of this period is Galileo, but many lesser heroes merit remembrance. Stevinus helped to determine the laws of the pulley and the lever; he made valuable studies in water pressure, the center of gravity, the parallelogram of forces, and the inclined plane; and at Delft, about 1690, he anticipated Galileo’s alleged experiment at Pisa by showing, contrary to immemorial belief, that when two like objects of however different weight are let fall together from a height they reach the ground at the same time.45 Descartes laid down quite clearly the law of inertia—that a body persists in its state of rest or in rectilinear motion unless affected by some external force. He and Gassendi anticipated the molecular theory of heat. He based his Météores (1637) on a cosmology no longer accepted, but the treatise did much to establish meteorology as a science. Torricelli (1642) extended his studies of atmospheric pressure to the mechanics of winds; these, he held, were the equalizing currents set up by local differences in the density of the air. Gassendi, that remarkable priest of all sciences, carried on experiments for measuring the speed of sound; his results gave 1,473 feet Per second. His friar friend, Marin Mersenne, repeated the experiment and reported 1,380 feet, closer to the current figure of 1,087. Mersenne, in 1636, established the whole series of overtones produced by a sounding string.
Research in optics centered on the complex problems of reflection and refraction, especially as seen in the rainbow. About 1591 Marco Antonio de Dominis, Archbishop of Spalato, composed a treatise, De radiis visus et lucis … et iride (published 1611), in which he explained the formation of the primary rainbow (the only one generally visible) as due to two refractions and one reflection of light in drops of moisture in sky or spray, and that of the secondary rainbow (an arc of colors, in reversed order, sometimes faintly seen outside the primary bow) as due to two refractions and two reflections. In 1611 Kepler’s Dioptrice studied the refraction of light by lenses; and ten years later Willebrord Snell of Leides formulated the laws of refraction with a precision that made possible a more accurate computation of the action of lenses on light and the construction of better microscopes and telescopes. Descartes applied these laws to a mechanical calculation of radiation angles in the rainbow. Explanation of the color arrangement had to wait for Newton.
Gilbert’s epochal discussion of terrestrial magnetism set off a train of theories and experiments. Famianus Strada, of the Society of Jesus, suggested telegraphy (1617) by proposing that two men might communicate through a distance by utilizing the sympathetic action of two magnetic needles made to point simultaneously to the same letter of the alphabet. Another Jesuit, Niccolo Cabeo (1629), gave the first known description of electrical repulsion. Still another, Athanasius Kircher, described in his Magnes (1641) a measurement of magnetism by suspending a magnet from one pan of a balance and counterpoising its influence by weights in the other. Descartes ascribed magnetism to the conflict of particles thrown off by the great vortex from which he believed the universe had evolved.
Alchemy was still popular, especially as a royal substitute for debasing the currency. Emperor Rudolf II, the electors of Saxony, Brandenburg, and the Palatinate, the Duke of Brunswick, the Landgrave of Hesse, all engaged alchemists to manufacture silver or gold.46 From these experiments, from the needs of metallurgy and the dyeing industry, and from the emphasis of Paracelsus on chemical medicine, the science of chemistry was taking form. Andreas Libavius personified the transition. His Defense of Transmutatory Alchemy (1604) continued the old quest, but his Alchymia (1597) was the first systematic treatise on scientific chemistry. He discovered stannic chloride, was the first to make ammonium sulfate, was among the first to suggest blood transfusions as therapy. His laboratory at Coburg was one of the wonders of the city. Jan Baptista van Helmont, a wealthy nobleman who devoted himself to science and the medical service of the poor, placed his name among the founders of chemistry by distinguishing gases from air and analyzing their varieties and composition; he coined the word gas from the Greek chaos. He made many discoveries in his chosen field, ranging from the explosive gases of gunpowder to the inflammatory possibilities of human wind.47 He suggested the use of alkalis to correct undue acidity in the digestive tract. Johann Glauber recommended crystalline sodium sulfate as “a splendid medicine for internal and external use,” and “Glauber’s salt” is still used as an aperient. Both he and Helmont dabbled in alchemy.
All these “natural sciences” shared in improving industrial production and martial slaughter. Technicians applied the new knowledge of movements and pressures in liquids and gases, the composition of forces, the laws of the pendulum, the course of projectiles, the refining of metals. Gunpowder was used in mine blasting (1613). In 1612 Simon Sturtevant devised a method of producing coke—i.e., “coking” (cooking or heating) bituminous coal to rid it of volatile ingredients; this coke was valuable in metallurgy, as the impurities in coal affected iron; it replaced charcoal and saved forests. The making of glass was cheapened, hence windowpanes became common in this age. Mechanical inventions multiplied as industry grew, for they were due less frequently to the researches of scientists than to the skill of artisans anxious to save time. So we first hear of the screw lathe in 1578, the knitting frame in 1589, the revolving stage in 1597, the threshing machine and the fountain pen in 1636.
Engineers were accomplishing feats that even today would merit admiration. We have seen how Domenico Fontana aroused Rome by erecting an obelisk in St. Peter’s Square. Stevinus, as engineer for Maurice of Nassau, developed a system of sluices to control the dykes—guardian of the Dutch Republic. Giant bellows ventilated mines; complicated pumps raised water into towers to give pressure for houses and fountains in cities like Augsburg, Paris, and London. Truss bridges were built on the simple geometrical principle that a triangle cannot be deformed without changing the length of a side. In 1624 a submarine traveled two miles under water in the Thames.48 Jerome Cardan, Giambattista della Porta, and Salomon de Caus advanced the theory of the steam engine; Caus in 1615 described a machine for raising water by the expansive power of steam.49
Geology was still unborn, even as a word; the study of the earth was called mineralogy, and respect for the Biblical story of Creation checked all ventures in cosmogony. Bernard Palissy was denounced as a heretic for reviving the ancient view that fossils were the petrified remains of dead organisms. Descartes ventured to suggest that the planets, including the earth, had once been glowing masses, like the sun, and that as the planet cooled it formed a crust of liquids and solids over a central fire, whose exhalations produced geysers, volcanoes, and earthquakes.50
Geography progressed as missionaries, explorers, and merchants strove to extend their faith, their knowledge, or their sales. Spanish navigators (1567f explored the South Seas and discovered Guadalcanal and others of the Solomon Islands—so named in the hope of finding there Solomon’s mines. Pecho Paes, a Portuguese missionary, taken prisoner in Abyssinia (1588), visited the Blue Nile and solved an ancient riddle by showing that the periodic inundations of the Nile Valley were due to the rainy season in the Abyssinian highlands. Willem Janszoon was apparently the first European to touch Australia (1606), and Abel Tasman discovered Tasmania, New Zealand (1642), and the Fiji Islands (1643). Dutch traders entered Siam, Burma, and Indochina, but information about these countries and China came chiefly from Jesuit missionaries. Samuel Champlain, under orders of Henry IV of France, explored the coast of Nova Scotia and ascended the St. Lawrence River to the vicinity of Montreal. His followers founded Quebec and charted the lake that bears his name.
The mapmakers struggled to keep not too far behind the explorers. Gerardus Mercator (Gerhard Kremer) studied at Louvain and established there a shop for making maps, scientific instruments, and celestial globes. In 1544 he was arrested and prosecuted for heresy, but escaped serious consequences; however, he thought it prudent to accept an invitation to the University of Duisburg, where he became cartographer to the Duke of Jülich-Cleves (1559). In his life of eighty-two years he labored tirelessly to map Flanders, Lorraine, Europe, the earth. His famous Nova et acuta terrae descriptio ad usum navigantium accomodata (1568) introduced the “Mercator’s projection” maps, which facilitated navigation by representing all meridians of longitude as parallel to one another, all parallels of latitude as straight lines, and both sets of lines at right angles to each other. In 1585 he began to issue his great Atlas (we owe this use of the word to him), containing fifty-one regional maps of unprecedented precision and accuracy, describing the whole earth as then known. His friend Abraham Oertel rivaled him with a comprehensive Theatrum orbis terrarum (Antwerp, 1570). Together these men freed geography from its millennial bondage to Ptolemy and established it in its modern form. Because of them the Dutch maintained almost a monopoly on mapmaking for a century.