KEY AND INDEX 



1, 41; conceptions concern- 

 ing the earth, sky, etc., 1, 42; 

 the recognition of the pulse, 

 1,51; practical mathematics, 

 1, 52; science as science was 

 unknown, 1, 55. 



Egyptian seasons, three in num- 

 ber, 1, 36. 



Egyptian temples, oriented with 

 reference to the point at which 

 the sun rises on the day of 

 the summer solstice, 1, 34. 



Eighteenth-Century Medicine, 

 Chapter VII, 4, 182. 



Eleatic School, founded by 

 Xenophanes, 1, 114. 



Electricity, Progress in, from 

 Gilbert and Von Guericke to 

 Franklin, Chapter XIV, 2, 



259- 



Electricity and Magnetism, The 

 Modern Development of, 

 Chapter VII, 3, 229. 



Electricity, Oersted's experi- 

 ments with suspended mag- 

 netic needle, 3, 236; its rela- 

 tion to magnetism, 3, 238; 

 the discovery of the principles 

 of electro-dynamics, 3, 230; 

 the first electro-magnet, ibid.; 

 experiments of Michael Fara- 

 day, 3, 243; the first storage 

 battery, 3, 246; Seebecle's 

 battery, 3, 247; the "Hertz- 

 ian Waves," now used in wire- 

 less telegraphy, 3, 247; Pro- 

 fessor Thompson and the 

 nature of, 6, 92; relation of 

 gases to the conduction of, 

 ibid.; atomic character of, 5, 

 96; regarded as a form of 

 matter, 6, 97; Age of, 6, 15; 

 general chapter on, 6, 148; 

 theories as to what it is, 6, 

 149; multiform uses of, in 

 every-day life, 6, 149; Ben- 

 jamin Franklin's one-fluid 

 theory of, 6, 150; two-fluid 

 theory of, 6, 151; name de- 

 rived from Latin word elec- 

 trum, 6, 152; derivation of 

 the idea that it is a "fluid," 

 6, 153; modern views of, 6, 

 153; studies of Rumford, 



Young, Fresnel, and Davy, 

 leading up to modern theories, 

 6, 154; most recent views as 

 to the nature, 6, 155; cur- 

 rents of, simply aggregations 

 of free electrons, 6, 156; how 

 it is developed, 6, 159; 

 statical and dynamical, 6, 

 1 60; generation of, by walk- 

 ing on a wool carpet in cold 

 weather, 6, 160; amount gen- 

 erated by lightning, 6, 161; 

 the static machine, 6, 161; 

 the work of the dynamical 

 current, 6, 162; voltaic cell 

 for generating, 6, 163; the- 

 ories of electrical action, 

 6, 165; practical uses of, 6, 

 1 68; current of, used for pro- 

 ducing heat, 6, 169; dynamos 

 for generating, 6, 174; mech- 

 anism of its production by the 

 dynamo, 6, 181; amount 

 generated at Niagara Falls, 

 6, 189; transmission of, from 

 Niagara Falls, 6, 194; loss 

 in transmission of, as esti- 

 mated by Siemens, 6, 195; 

 transmission of, at Niagara by 

 recent methods, 6, 197; "step 

 up" and "step-down" trans- 

 formers, 6, 198; high 

 and low voltage, 6, 199; 

 Ruhmkorff coil, the construc- 

 tion of, 6, 199; traction en- 

 gines used in mining, 6, 257; 

 engine invented by W. M. 

 Schlessinger, 6, 257; in coal- 

 mining, 6, 266; electric light- 

 ing of mines, 6, 269; obtain- 

 ing nitrogen from the air by 

 the use of, 6, 307; and high 

 temperatures, 6, 313; the 

 discovery of, 8, 4. 

 Electric light, Sir Humphry 

 Davy's experiments with, 3, 

 234; first ever invented, by 

 Sir Humphry Davy, 6, 220; 

 first practical application of, 

 in France, 1849, 6, 222; the 

 improved arc light, 6, 226; 

 Chas. F. Brush's invention of 

 arc light, 6, 226; some recent 

 types of arc lights, 6, 227; 



[I 7 6] 



