522 INDEX. 



Paoe. 



Taylor, Mr. "W. B., illustrations by, of the refraction of sound 449, 450 



Telegraph, electro-magnetic, practicable with an "intensity" magnet 42 



Telegraph lines, relation of, to lightning 244 



Telegraph wires largely affected by induction 251 



Temperature and radiation of flame not proportional 358 



Ten Eyck, Dr. Philip, co-operation of, in experiments in develop- 

 ing electro-magnetism 40 



Ten Eyck, Dr. Philip, independent experiments by, in developing 



magnetism in soft iron 47 



Tertiary induction current, nature of 181 



Testing building materials 344 



Thermo-galvanometer, application of, to meteorology, etc. 215 



Thermo-galvanometer applied to detect distant radiation 283 



Thunder-cloud, Becquerel's theory of 190 



Thunder-storms, on the effects of 193 



Thunder-storms, theory of, by some French writers 103 



Topographical sketch of New York 8 



Transparent bodies differently permeable to phosphorescence 210, 211 



Transverse re-action of galvanism and magnetism, difficult of ex- 

 planation 305 



Trenchard, Commodore Stephen D., co-operation of, in observations 



on sound 433 



Trinity House investigations in sound, by Dr. John Tyndall 444, 451 



Trumpet, relative audibility of, in different directions 402 



Trumpets of different materials and shapes compared 401 



Tuberville, Dr., observations by, on color-blindness 235 



Tyndall, Dr. John, hypothesis by, of hygroscopic " flocculence " ob- 

 structing sound 445, 451, 485 



Tyndall, Dr. John, observations by, on the aerial echo 454, 457 



Tyndall, Dr. John, present at meeting of Philosophical Society of 



Washington 416 



Upshur, Captain John H., co-operation of, in observations on sound 433 



Ure, Dr., experiment by, with galvanism on body of dead malefactor 160 



Van Marum, luminosity of electrified wire observed by 102 



Vapor, remarks on the diffusion of 288 



Variable range of sound 409 



Velocity of projectiles, a method of determining 212 



Vessels employed for observing sound in different directions 433, 434, 



437, 453, 458, 465, 477, 483 



Vision, defective, prevalence of . 233 



Vitality not a mechanical force 223 



Wade, Major, machine devised by, for testing strength of materials 348 



Walker, Commander John G., co-operation of, in observations on 



sound 426 



