324 Scientific Intelligence. 



T= 1877, Jan. 18-9658, Wash. M. T. 

 7i — 174° 15' 32" ) 



Q = 187 10 4 V Apparent Equinox, Feb. 13-7. 

 *=152 20 28 ) 

 logy =990709 

 The constants for computing the rectangular coordinates are : 

 x' = 9-90639 sin (250° "7068+ v) sec *\v 

 y' - 9-71223 sin (336 '7634+») sec »|» 

 z' = 9-79456 sin (343°-4010+-y) sec *£» 

 2. Note on the Photographic Spectra of Stars : by William 

 J!i GKJTS8, D.C.L., LL.D., F.R.S. (From the Proceedings of the 

 Royal Society, No. 176, 1876).— In the year 1863 Dr. Miller. and 

 brum of Sirius. "On 

 . mill on the 3d of March of the same vear, 

 when the spectrum of this star (Sirius) was caused to fall upon a 

 ■•ollodion surface, an intense spectrum of the more 

 refrangible part was obtained. F,- ( „n want of accurate adjustment 

 rag, or from the motion of the star not being exactly com- 

 pensated by the clock movement, or from atmospheric tremor, the 

 spectrum, i lined at the edges, presented no 



indications of lines. Our other investigations have hitherto pre- 

 vented us from continuing these experiments further; but we 

 oi parson g them."* I have 

 wase experiments by the aid of the 18-inch 

 belonging to the Royal Society's telescope in my 

 possession. Considerable delay has arisen from the necessity, for 

 these observations, of a more uniform motion of the driving-clock. 

 1 or this purpose, Mr. Howard Grubb has successfully applied to 

 the clock the control of a seconds pendulum h 

 with a sidereal clock. This system works quite satisfactorily. 

 The prisms employed are made of Iceland spar, and the lenses of 

 qttart /. After an extensive trial of different photographic processes, 

 preference has been given to dry plates. The apparatus is so 

 arranged that a solar or electric spectrum can be taken on the 

 same plate, for the purpose of < . spectrum of 



the star. Spectra have been obtained of Sirius, Vega, Venus, the 

 I do not purpose in this preliminary notice to describe 

 m detail the arrangements of the special apparatus which has 

 oeen constructed, nor to offer the results of the experiments in 



their present incomplete state to the Royal Society. Still I 

 ^1 U L pe } hat ' even in this earl y stage of the inquiry, the 

 enlarged copy of the spectrum of Vega (a Lyra) w! i 

 pames this note may not be regarded^ UoleTher unworthy of 

 * Phil. Trans., 1864, p. 428. 



