INDEX. 



473 



Stahl, chemical theory of 52 



Stems bend to indigo rays 413 



Stokes on electric light 125 



Strontian, flame of 55 



Substitution, theory of 104 



Sun, force derived from 187 



" surface of, its condition 81-83 



Swan on yellow ray 63 



Systemic circulation 370 



T. 



Thermo-electric couples 327 



" currents 328 



" pairs, effect of num- 

 ber of 334 



" pairs, improved 



forms of 336 



" quantity 333 



" thermometer 327 



Thickness, effect of, in sensitiveness . 238 



Tides in mercury 346 



Towson on camera 211 



Transmission from retina to brain. . . 109 



Tyndall on distribution of heat 385 



" on electric light 390 



" on ignition of platinum 433 



" on spectrum 384 



U. 



Undulations and colors 123 



" interpretation of, by 



brain ... 122 



length of. 121 



Undulatory theory, power of the 117 



Unit lamp 45 



V. 



Vertical element of flame analyzed.. 55 

 Vibrations connected with tempera- 

 ture 36 



effect of, on retina 108 



" spectrum measure of 128 



Virginia, experiments made in 197 



; ' spectrum 89,90 



Vision and photographic impressions. 2 1 



hypothesis of 101 



" inverse Ill 



Vital force, rejection of 131 



Vogel, Professor, on increased sen- 

 sitiveness 451 



W. 



Water, decomposition of. 1 88 



' ' decomposition of, under press- 

 ure 363 



" not decomposed by light 294 



Wave-lengths as spectrum meas- 

 ures 113, 127 



" " interpretation of, by 



brain 122 



" " measures of 12L 



Wedgwood on ignition of gold and 



earthenware 28 



Wilson's experiments on phospho- 



ri 318 



Wollaston on spectrum 88 



Y. 



Yellow ray most luminous 105 



Young discovers interference 116 



THE END. 



