14 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



per's photograph gives 293. The diffraction plate used by 

 Dr. Draper was prepared for him by Mr. L. M. Rutherford, by 

 a machine devised and constructed by that well-known 

 amateur. It consists of a plain glass surface, a portion of 

 which, equal to about one square inch, is ruled with a fine 

 diamond point with 6481 lines to the inch. Owing to the 

 fineness of details brought out by Draper's photographs, he 

 is justified in the statement that the exact composition of 

 even a part of the spectrum of any metal will not be known 

 until we have obtained photographs of each on a large scale. 

 4 D, 1873, yi., 400. 



THE SOLAR PHENOMENA. 



M. Gautier has given a resume of spectroscopic observa- 

 tions on the solar spots made at Geneva during the past 

 three years. His results are mainly a confirmation of those 

 of other observers. The protuberances are classed under 

 three heads : as eruptions, exhalations, and detached forma- 

 tions. Like Father Secchi, he was often struck by the fact 

 that when a protuberance is observed near either pole there 

 is generally one symmetrical with it at the other end of 

 the corresponding solar diameter, and near the opposite 

 pole. 



The decrease in the number and dimensions of protuberan- 

 ces appears to precede and exceed that of the spots. Gau- 

 tier adheres to the hypothesis of spots being formed by sco- 

 rial matters, resulting from cooling of the surface by radia- 

 tion. 12 A, 1873, IX., 494. 



EFFECT OF TEMPERATURE OF THE SPECTROSCOPIC APPARATUS 



ON THE SOLAR SPECTRUM. 



Mr. Hennessey has made some observations to determine 

 the amount of displacement in the solar spectrum arising 

 from changes of temperature. The spectroscope was set up 

 on a pillar within a small tent, at a time of the year when 

 the thermal range is considerable. The result of the series 

 shows that a displacement equal to four divisions of Kirch- 

 hoff's scale are produced by a change in temperature of thirty 

 degrees, from which it appears that this subject may not be 

 neglected in investigations made under a considerable ther- 

 mal range. Pr. Roy. Soc. of London, XXII., No. 150. 



