J.\/)/-:\ TO VOLUME II. 



489 



SOI.AK IMIVSIC8. 



Siemens'*. < '. W., IL'.'I : by -Imnkarje. 

 H'-lmhult/'s, 121): inieivepiion <>f 

 radiant heat l>y vapour nf \v:it<-r 

 and gaseous compounds. 421) ; lu- 

 minosity of dust -part ides by elee- 

 Irificntion observed by Siemens, 

 W.T., 432 ; metalloids, non-exist- 

 ence in sun contended for by 

 Loekyer, J. N., 427 ; (nu-tfurifrx, 

 ttccludnl ijam-x in, analysis of by 

 Dr. Flight, 420 ; not passing 

 through our atmosphere, 420) ; 

 oxygen, existence of, in sun, ac- 

 cording to Draper, 427 ; solar 

 absorption spectrum, explanation 

 of, 431 ; stellar space supposed 

 tilled with highly rarefied gaseous 

 matter, 425 ; ultra violet rays, 

 absorption of by clear glass, 430 ; 

 variation of solar heat due to sun's 

 travelling through space, 431 ; 

 velocity, rotative of, high, zodiacal 

 light due to, according to Mai ran, 

 opposed by La Place, 427 ; zo- 

 diacal light, Mairan's views re- 

 proposed, 432. 



Solar physics, questions involved in, 

 445. 



Solar spectrum , researches by Bunsen , 

 445; Muggins, W., 446; Kirch- 

 hoff, 4 It;. 



Solar temperature, equal to that of 

 large electric arc, or 3000' ('.. 

 448. 



Solution of crystalline substances, 

 system of refrigeration by, 32*!. 



Soundings, actual and with batho- 

 meter, 372 ; cable lost, recovered 

 by, 380 ; contour lines of Atlantic 

 taken, 380 ; illustration, practical, 

 on Faraday, 380; position ob- 

 tained by, 380 ; without soundii g 

 line, principle of method, 358. See 

 Deep-sea soundings. 



Spectrum analysis proves gases in 

 space. 420. 



Spiral spring to measure terrcstiiul 



STEEL. 



attraction proposed by Hcrschel. 

 169. 



Spoerer, Dr., on sun's temperature. 

 27,000 ('.. 4 :<.->. 



Standard measure of length, referable 

 to earth's quadrant, 3t>0. 



Standard unit of decimal measure, 

 305. 



Steam blower for producing vacuum 

 superior to steam engine with 70- 

 Ibs. steam, inferior to with 35-lbs. 

 to 40-lbs., 320. 



Steam engine and steam blower, 

 comparison of, 320. 



Steam of high pressure for marine 

 boilers, 38!>. 



Steel bar, experiments on, 413. 



Steel, cast, three times strength of 

 iron up to elastic limits, 310. 



Si eel, corrosion of, of different tem- 

 pers, 39(! ; expansion of, Duloiiir 

 and Petit's experiments, 30* : 

 furnace, Bessemer metal melted 

 in, 307 ; and iron, difference be- 

 tween, 412 (mild, for boilers, 398 ; 

 contains 99'6 per cent, of metallic 

 iron, 398 ; elongated 25 per cent., 

 398 ; loaded to half breaking strain, 

 398 ; produced in quantities of 

 10 to 12 tons) ; plates and wrought 

 iron, not easily detected, 310 ; 

 rails, Struve's objection to, 308 ; 

 sleepers at low cost, 416 ; specific 

 gravity of, greater than iron, 310 : 



(spring*, coefficient of variation 

 of elasticity with temperature 

 of, 369 ; Siemens's, C. W., experi- 

 ments on, 309 ; variation of, 

 dependent on hardness, 370 ; 

 Wertheim's investigations on. 

 369) ; tested to 100 tons to square 

 inch for New York bridge, 398 ; 

 wire and solid steel, strength <>f. 

 405, 407 ; wire, strength of, in- 

 creased by wire drawing and oil 

 hardening, 407 ; for telegraphs 

 tested to 80 to 90 tons, 399 ; yield- 



