Newton was born in England the same year that Galileo died in Italy. His greatest work is presented in his celebrated "Principia," or "Mathematical Principles of Natural Philosophy," in which the law of gravitation, the laws of motion, and the mathematical principles of mechanics are developed. The "Principia" was published in 1687, and it has ever since been regarded as the corner stone of mathematical and physical science.
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.