22 PROGRESS OF SCIENCE. 



mesenteric glands ; traced the tendons, the ligaments, and 

 THE NERVES. Many of the names used by him and 

 Erasistratus are still accepted ; advanced anatomy and 

 physiology through his pursuit of dissection and vivisection 

 of animals and human bodies. ANATOMY, with and after 

 him, became the basis of medical teaching. The school of 

 medicine he and Erasistratus founded was famed for nearly 

 700 years. 



323 283. Euclid compiled his book on GEOMETRY a 

 standard work to this day. He taught that light travels in 

 straight lines called " rays." 



300260. Erasistratus, who, like Herophilus, was a 

 worthy follower of Hippocrates, was a great anatomist. 

 He described THE BRAIN and its division into two parts 

 the cerebrum and the cerebellum and pointed out its circum- 

 volutions. He described the STRUCTURE OF THE HEART, 

 and discovered it to be the fountain-head of arteries and 

 veins ; recognised TWO KINDS OF NERVES, those of motion 

 and those of sensation, and their connection with the brain, 

 apparently understanding the brain to be the thinking and 

 feeling apparatus. 



287212. Archimedes, a mathematical and inventive 

 genius of the highest order, exceeded by none, possessing at 

 once marvellous originality of conception and immense 

 working power, discovered new provinces of inquiry. He 

 showed " how mathematical theory could be wedded to 

 physical experiments." His works are the application of 

 Aristotle's inductive process in a new field, if they do not 

 constitute by themselves the first true organum, as some 

 writers would have it. He measured the SPHERE, the 

 CYLINDER; discovered the LAW OF THE LEVER the 

 primary law of mechanics and the base of STATICS ; he 

 invented a planetarium representing the movements of 

 the heavenly bodies ; he invented, i, the SPIRAL-PUMP 

 (also called water-screw, screw of Archimedes, and cochlea) ; 

 2, CONCENTRIC MIRRORS ; 3, POWERFUL LIFTS ; 4, GIGANTIC 

 CATAPULTS. The three last inventions were, if we are to 

 believe Roman writers, used with tremendous effects against 

 the Romans who were besieging Syracuse. He founded 



