154 THE WONDERFUL CENTURY. CHAP. zv. 



1. The foundation of modern Chemistry by Black, 

 Cavendish, Priestley, and Lavoisier; and 



2. The foundation of Electrical science by Franklin, 

 Galvani, and Volta. 



The seventeenth century is richer in epoch-making 

 discoveries, since we have : 



3. The theory of Gravitation established. 



4. The discovery of Kepler's Laws. 



5. The invention of Fluxions and the Differential 

 Calculus. 



6. Harvey's proof of the circulation of the Blood. 



7. Roemer's proof of finite velocity of Light by Jupi- 

 ter's satellites. 



Then, going backward, we can find nothing of the first 

 rank except Euclid's wonderful system of Geometry, 

 derived from earlier Greek and Egyptian sources, and 

 perhaps the most remarkable mental product of the 

 earliest civilizations; to which we may add the introduc- 

 tion of Arabic numerals, and the use of the Alphabet. 

 Thus in all past history we find only eight theories or 

 principles antecedent to the nineteenth century as com- 

 pared with twelve during that century. It will be well 

 now to give comparative lists of the great inventions and 

 discoveries of the two eras, adding a few others to those 

 above enumerated. 



OF THE NINETEENTH 

 CENTURY. 



1. Railways. 



2. Steamships. 



3. Electric Telegraphs. 



4. The Telephone. 



5. Lucifer Matches. 



6. Gas Illumination. 



OF ALL PRECEDING AGES. 



1. The Mariner's Compass. 



2. The Steam Engine. 



3. The Telescope. 



4. The Barometer and Tlier 



mometer. 



5. Printing. 



