INDEX. 521 



Page. 

 Solar spots, heat radiated from, less than from surrounding parts_. 224, 226 



Solar spots, apparatus employed in observing 225 



Soul of man not the motive power of his body 312 



Sound, abnormal phenomena of, noticed in the cannonading of 



battle 420 



Sound-beams very divergent at a distance 388, 421 



Sound, direct and reflected, limit of perception between 295 



Sound distinctly heard against the wind indicative of a change in 



its direction 43G 



Sound, general conditions of audibility of 506 



Sound greatly influenced by reversed upper currents of air 423 



Sound, intermittent rangeof 409, 496, 497 



Sound, penetration of, dependent on quantity rather than intensity 490 



Sound propagated to great distances along the surface of water 400 



Sound reflectors of little use for distant propagation 381, 405, 409 



Sound, refraction of, by favoring or adverse currents of wind 449, 507 



Sound sometimes heard at greater distance against the wind 380, 404 



Sound, tendency of, to rise against adverse wind 388 



Sound, the range of, influenced by the direction of the wind. 4G4, 4G7, 475 



Spark increased from flat spiral of copper ribbon 87, 88 



Spark, etc., from long conductor, observations on 87, 103 



Spark, intense, on short wire connecting large flat spiral 88 



Spiral conductor, increase of self-induction through 89, 92, 95, 97 



Spiral conductor, influence of, on galvanic current 108 



Spiral, flat, of copper ribbon, strong sparks from 87 



Spots (solar), observations on their relative radiation 224 



Spurzheim, observations by, on color-blindness 235 



Steam, chemical and mechanical eflects of 1 



Steam, electricity from 189 



Steam-pressures, and relative distances of fog-signal sounds 398 



Steam-whistle and ti'umpet compared for penetration 402 



Steam-whistle as a fog-signal 382,394,400 



Stevens, Mr., application by, of clock-escapement for fog-bells 374 



Stimpson, Dr. "William, observations by, on fog 372,373 



Stokes, Prof. Geo. G., theory by, of the action of wind on 



sound .— 390, 414, 419, 448 



Sturgeon, Mr. William, improvement by, in electro-magnetic ap- 

 paratus . 3,7,37 



Sturgeon, Mr. William, observation by, on alternation of successive 



orders of induction currents 159 



Sturgeon, Mr. William, observations by, on diflerent armature coils 



of magneto-electric machine 117 



Sturgeon, Mr. William, observation by, on substituting bundle of 



wireforsolid iron 126 



Successive induction currents 127 



Successive orders of induction from ordinary electrical discharge 185 



34 



