MIRACLES OF SCIENCE 



Selenium, its curious properties 

 illustrated by Mr. Hammer, 

 313 ; its use in sending pictures 

 by wire, 315. 



Sheep, a hornless race developed 

 along Mendelian lines, 197. 



Ships, steadied at sea by the 

 gyroscope, 266. 



Sperry, Mr. Elmer A., perfects 

 the gyro-compass, 265 ; applies 

 the gyroscope to the stabilizing 

 of ships, 269; uses the gyro- 

 scope to stabilize the airship, 

 276. 



Sphinthariscope, invented by Pro- 

 fessor Crookes; used to make 

 the impact of atoms visible, 118. 



used in testing the double stars, 

 96; its most delicate feats sur- 

 passed by the electroscope, 115. 

 Spectroscopic binaries, how they 

 are weighed, 93 ; first discovered 

 by Miss Maury at Harvard Ob- 

 servatory, 1889, 95 ; their periods 

 of revolution, 97. 

 Side-Chain theory of Professor Spectrum, the Zeeman effect as 



Ehrlich, 225. revealed in, 104; light beyond 



Siedentopf, developer of the ultra- the visible, 106. 



microscope, 232. 

 Sirius, a binary having more than 



three times the mass of the 



sun, 93. 

 Sleeping sickness, a tentative 



remedy discovered by Ehrlich, 



230. 

 Smith, Dr. Theobald, discovers 



that ticks transmit cattle plague, 



245. Star clusters, their shape and lo- 



Sodium, its spectral lines and cation, 23, 



what they reveal, 104. Stars, the life history of, 23; ex- 



Solar system, as explored by an amples of white, 23 ; examples 



imaginary aviator, 29; its iso- 

 lation in space, 32; seemingly 



not far from the center of the 



universe, 58. 

 Solar constant, determined by 



Professor C. G. Abbott, and 



shown to be in reality a vari- 

 able, 108. 

 Solution, of common salt, its true 



character, 102. 

 Species, the creation of, Chapter 



VI, 170. 



Specifics, the search for, 228. 

 Spectrograph, used by Professor 



Campbell to test star speeds, 



47. 

 Spectroheliograph, reveals com- 



position of sun's atmosphere, 37. 

 Spectroscope, its analysis of nebu- 

 lae, 21; its analysis of stars, 

 23 ; used by Huggins in astrono- 

 my in 1863, 33; its revelations 

 of the movements of stars, 36; 

 used to measure the earth's 

 flight, and thereby to determine 

 the sun's distance, 77; the slit, 



340 



of red, 24; their cyclic revolu- 

 tion, 24; the new star in Per- 

 seus, 25, 27; their distances in 

 contrast with distances in the 

 solar system, 31; of the 20th 

 magnitude, revealed by Mt. Wil- 

 son reflector, 35 ; their radial 

 motion tested by the spectro- 

 scope, 36 ; their average speed, 

 39 ; their proper motion and 

 their seeming shifts of posi- 

 tion, 40; their speed measured 

 by Professor Kapteyn, 42 ; 

 the apparent motion of our 

 nearest neighbor, Alpha Cen- 

 tauri, 42 ; how their distances 

 and speeds are measured, 44 ; 

 testing the parallax of, 45, 

 46 ; new stars move slowly and 

 old stars rapidly, 48 ; their vary- 

 ing speeds at different ages 

 tentatively explained by Pro- 

 fessor Campbell, 50 ; many that 

 are brighter than the sun are 

 relatively near; some are 100,- 

 000 times as bright as the sun, 



