INDEX. 



455 



Pressure low near photosphere, 405 

 Prism, 4 



experiments with, Newton, 6 

 comparison, 73 



Prominences, eruptive, 115, 419, 420 

 forms of, 115 ; like trees, 415 ; 



metallic, 415, 421 ; spectra of, 



method of comparison of, 348 ; 



metallic, Young's observation, 



416 



nebulous, 116 

 quiet, 413, 421 

 rate of up-rush, 416, 417 

 spectrum of, 343 

 Purification of spectrum, 24 



R. 



Radiation and absorption, law of 



equivalence of, 63 

 researches by Balfour Stewart, 53 

 solar, 444 



Radicals, organic, 271 

 Refrangibility, changes of, Vogel, 



369 

 change of iron lines, 347. See 



Contortions 



Respighi accepts classification of pro- 

 minences, 116 



observations on chemical composi- 

 tion of prominences, 116 

 Reversal phenomena, 223 

 Ricco, 324 

 Robinson's remarks on electric 



spectra, 147 

 Roberts-Austin, 278 



research on gold-copper alloys, 



152 

 Roscoe, quoted, 272 



on sodium vapour, 277 

 on potassium vapour, 277 

 Rotation of photosphere, 426, 427 

 Russell, Doctor, work on absorption, 



276 



Rutherfurd's gratings, 85 

 spectra of stars, 173 



S. 



Sale t' s work on spectra of metalloids, 



193 



Scheiner, 425 

 Schuster on spectra of elementary 



bodies, 192 ; on oxygen, 285 

 Seabroke's and Lockyer's method of 



observing the chromosphere, 114 



Secchi accepts classification of promi- 

 nences, 116 

 explanation of the contortion of 



lines, 133 

 observes prominences on disc, 



117 



observations on chemical composi- 

 tion of prominences, 117 

 records spectra of stars, 173 

 Separations exhibited by arc, 387, 



393 



Sharpey suggests the word " chromo- 

 sphere," 110 

 Sherman, Young's work at. See 



Young. 

 Shifts, 369 



Siemens' machine, arc of, 379, 383 

 Simms, improvement in spectroscope, 



26 

 Slit, first used, 23 



Kirchhoff's addition, 72 



line is an image of, proof of, 



146 



plate, description of, 103 

 Smyth's, Piazzi, experiments on solar 



spectrum, 64 



Sodium, D line, phenomena of, 222 ; 

 explanation by Stokes, 51 ; in- 

 vestigation of, by Foucault, 50 

 experiments on, 128, 129 

 flutings of, 294 

 in sun, 57 



spectra of, in tubes. 299 

 vapour in sun-spots, 130 

 vapour of, Roscoe, 277 

 Sound, analogous to light, 87 

 Sirius, lines in spectrum of, 201 ; 



predicted, 250 

 Spark in flame, action of, 293 



spectrum of, as compared with that 



of sun-spots, 340 

 Spectra, coincident lines in various, 



general statements on, 153 

 discontinuous, 31 

 fluted, and line spectra, difference 



between, 180 



fluted, observation on, Hittorf, 

 179; Mitscherlich, 179; Pliicker, 

 179 



gaseous, researches on, Frankland, 

 131 ; result of researches on, 

 126 



long lines common to many, 153 

 multiple, Angstrom's view on, 191 ; 

 discovered by Pliicker, 190 ; 

 Mitscherlich, 190 ; Hittorf, 190 ; 

 of compounds, 159; conclusion 

 on, Mitscherlich, 159 



