114 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



one continuous line, and a second reading when any given 

 line has been superposed upon any other line at a moderate 

 distance from it, the difference between these readings will 

 enable us at once to ascertain the distance between the lines, 

 if the micrometer be calibrated in terms of the spectrum as 

 seen in the observing telescope. 



Thalen has published the results of a joint investigation 

 made by Angstrom and himself (but not published till after 

 the former's death) upon the spectra of the metalloids, an 

 excellent abstract of which by Schuster appears in Nature. 

 They believe it extremely improbable that any lines present 

 in a spectrum at a lower can disappear at a higher tempera- 

 ture. The electric spark and the actions it may cause are 

 carefully studied, and applied to elucidate the carbon spec- 

 trum. 



Boisbaudran has given, in a plate illustrating an extended 

 paper on gallium, an excellent representation of the spec- 

 trum of this metal, together with all the other elemental 

 lines which are found in the same vicinity. 



Cleyden and Heycock have discovered the significant fact 

 that the spectrum of indium, which is obtained by taking 

 the electric spark between electrodes made of that metal, is 

 quite different from that ordinarily given. Instead of three 

 lines only, they found sixteen under the above circumstances. 

 The lines usually figured are two in the indigo and one in 

 the violet; they have wave-lengths, as given by Thalen, of 

 4532, 4509, and 4101 tenth-meters; the authors believe that 

 the middle one should be 4510. The new lines have wave- 

 lengths as follows: 6906, 6193, 0114, 6095, 5922, 5905, 5862, 

 5820, 5722, 5644, 5250, 4680, 4656, 4638, 4510, and 4101 

 tenth-meters. The first line is remarkable, since potassium, 

 strontium, and antimony only give less refrangible lines. 



Henry Draper has discovered the remarkable fact that 

 oxygen exists in the sun, and that it and probably also the 

 other metalloids show their presence in the sun-spectrum by 

 bright instead of dark lines. By means of photography he 

 has produced upon a single plate the solar spectrum from 

 just above G to below II, and the spectrum of air ignited 

 by a powerful spark between iron and aluminum terminals. 

 Since the lines of iron in the latter spectrum coincide exactly 

 with known iron lines in that of the sun, the non-shifting of 



