ANNUAL ADDRESS. 179 



cultations, and just missed discovering the law of gravitation. 

 He laid the foundation for practical application of astronomy to 

 every-day life. 



In the eighteenth century astronomy was recognized by gov- 

 ernments as no longer of merely curious interest and its students 

 received abundant aid. The improvement of the telescope, the 

 discov^ery of the law of gravitation and the invention of logarithms 

 had made possible the notable advance marking the close of the 

 seventeenth century. The increasing requirements of accuracy 

 led to exactness in the manufacture of instruments, to calculation 

 and recalculation of tables, to long expeditions for testing methods 

 as well as conclusions, until finally the suggestions of Coperni- 

 cus, the physician, and of Kepler, the ill-fed invalid, became fact, 

 and astronomical results were utilized to the advantage of man- 

 kind. The voyager on the ocean, the agriculturist on land, reap 

 benefits from the accumulated observ^ations of three centuries, 

 though they know nothing of the principles or of the laborers 

 by whom the principles were discovered. The regulation of 

 chronometers as well as the fixing of boundary lines between 

 great nations are determined by methods due to slow accumu- 

 lation of facts, slower development in analysis and calculation, 

 and even slower improvement in instruments. 



Galvani's observation that frogs' legs twitch when near a 

 friction machine in operation led him to test the effect of atmos- 

 pheric electricity upon them. The instant action brought about 

 the discovery that it was due, not to atmospheric influence, but 

 to a current produced by contact of a copper hook with an iron 

 rail. Volta pursued the investigation and constructed the pile 

 which bears his name. With this, modified, Davy, in 1807, 

 decomposed potash and soda, thereby isolating potassium and 

 sodium. This experiment, repeated successfully by other 

 chemists, was the precursor of many independent investigations 

 which directed to many lines of research, each increasing in in- 

 terest as it was followed. 



Volta' s crown of cups expanded into the clumsy trough bat- 

 teries which were finally displaced in 1836 by Daniel's constant 

 battery, using two fluids, one of which was cupric sulphate. De 



