SCIENCE AND PROGRESS 



lines. In the one instrument, as in the other, the 

 rays are made to converge by being reflected from 

 a concave surface. The laws of reflection appear 

 to have been well known to the geometers of Plato's 

 school ; they are fully treated in the book on Optics 

 ascribed to Euclid ; they must certainly have been 

 familiar to the greatest geometer of that time. So, 

 too, the general nature of refraction; for burning- 

 glasses and magnifiers of crude form are mentioned 

 by Pliny and others. Had he pushed his contriv- 

 ance of burning-mirrors one step further he would 

 have had a telescope. Galileo and the proof of 

 the Copernican theory would have been antedated 

 eighteen centuries. The extraordinary list of Ar- 

 chimedes' inventions pulleys and windlasses, cata- 

 pults, the water-screw or screw-pump, the endless 

 screw, various hydraulic and compressed-air ma- 

 chines, great swift-acting cranes to seize the Roman 

 galleys and swing them out of the water, and no end 

 of others, attest his inventive genius. But all this 

 seems to have been a diversion, a recreation, much 

 of it done simply for his patron and friend, the King 

 Hiero. He does not seem to have taken any es- 

 pecial interest in the study of natural phenomena, 

 as Newton and Galileo did. He was not an experi- 

 mental or observing genius ; he was a mathematical 

 giant, and that study absorbed all his interest. 

 Archimedes belonged to the generation next after 



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