NEW CONCEPTIONS IN SCIENCE 



from the Hindus. It is, therefore, probably the 

 Hindu and not the Arabic system of notation, and 

 belongs back centuries before our era. Algebra 

 seems not to have been known to Archimedes, or 

 even to Ptolemy ; it appears not to have come into 

 use before the days of the illustrious Hypatia. The 

 foully murdered Alexandrian composed a com- 

 mentary on the work of Diophantus, which is the 

 earliest treatise recorded. The application of al- 

 gebra to geometry we owe to Descartes, the con- 

 temporary of Galileo; the invention of the calcu- 

 lus to Leibnitz and Newton. Though the germ of 

 the theory of logarithms appears to have been 

 known to Archimedes, the first elaborate system 

 was constructed by Baron Napier in 1614. The 

 telescope found its first notable triumph in the 

 hands of Galileo, again ; the barometer was the in- 

 vention of his pupil, Torricelli. A convex lens of 

 rock-crystal was found by Layard among the 

 ruins of the palace of Nimrud ; the principle of the 

 microscope, then, was known in the most ancient 

 times ; but it found little practical use until it was 

 taken up by Leeuwenhoek and Robert Hooke, who 

 contested with Newton the discovery of the law of 

 gravitation. The galvanometer, the first accurate 

 measurer of electricity, belongs to the last century. 

 Strictly industrial inventions have contributed 

 not less. The steam-engine, the voltaic pile, the 



24 



