TECHNICAL INDEX AND GLOSSARY 



p. 267; Arabian Astronomy, Vol. II, p. 14; "Copernicus to Kepler 

 and Galileo," Vol. II, p. 52; "Newton and the Law of Gravita- 

 tion," Vol. II, p. 236; "The Successors of Newton in Astronomy," 

 Vol. Ill, p. 3; "The Progress of Modern Astronomy," Vol. Ill, 

 p. 19; "Solar and Telluric Problems," Vol. V, p. 205. Numerous 

 minor references might be added, but the above outline the main 

 story of astronomical progress. 



Atlantic Cable. The first cable across the Atlantic was pro- 

 jected by Cyrus W. Field in 1856. After unsuccessful efforts, 

 the first electric message was sent across the ocean in August, 

 1858. This cable soon parted, however, and a permanent con- 

 nection was not established till 1866. See "The Submarine 

 Cable," Vol. VIII, p. 30. 



Atmosphere. The "ocean of air in which we live" has been 

 investigated scientifically chiefly within the past century. Its 

 composition, as regards the chief constituents, oxygen and 

 nitrogen, was determined toward the close of the eighteenth 

 century; but the minor gases, argon, neon, crypton, and xenon, 

 escaped detection for about a hundred years, when they were 

 discovered by Lord Rayleigh and Sir William Ramsay. See 

 Vol. V, p. 82. For meteorological aspects of the atmosphere, 

 see Vol. Ill, p. 168. 



Atom. The unit structure of matter as viewed by the chemist. 

 The atomic theory of matter in its modern scientific develop- 

 ment dates from the time of John Dalton, who propounded the 

 theory in 1803. See "John Dalton and the Atomic Theory," 

 Vol. IV, p. 38. 



Atomic weights. Each specific atom has a definite weight, 

 which chemists have been at great pains to discover. For table 

 of atomic weights, see "Element," in the present glossary. 



Aurora Borealis. A manifestation of lights seen at irregular 

 intervals toward the polar regions; believed to be of electrical 

 origin. The most recent explanation of the phenomenon is that 

 of Arrhenius, who thinks the light due to electrons thrown out 

 from the sun and accumulated in the upper atmosphere, where, 

 under magnetic influence, they tend to move toward the poles. 

 See "The Aurora Borealis," Vol. Ill, p. 172. 



Automatic Coupling. A life and limb saving device for coupling 

 freight cars without the direct intervention of human hands. 

 An effective coupler was introduced by Eli Janney in 1879. See 

 "Automatic Couplings," Vol. VII, p. 147. 



Automobile. The familiar self-propelled vehicle, actuated 



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