1863.] 



43 



December 10, 1863. 



Major-General SABINE, President, in the Chair. 



The President announced that he had appointed the following Members 

 of the Council to be Yice-Presidents : — 



The Treasurer. 

 Dr. Falconer. 

 Dr. Hooker. 

 Professor Wheatstone. 

 The Rev. Professor Willis. 



The Very Reverend Dr. Stanley, Dean of Westminster, was admitted 

 into the Society. 



The following communications were read : — 



I. " On the Spectra of some of the Chemical Elements.^^ By 

 William Huggins, Esq., F.R.A.S. Communicated by Dr. 

 W. A. Miller, Y.P. and Treas. R.S. Received November 5, 

 1863. 



(Abstract.) 



The author has been engaged for some time in association with Prof. 

 W. A. Miller in observing the spectra of the fixed stars. For the purpose 

 of comparing the spectra of these wdth the spectra of the terrestrial 

 elements, no maps of the latter were found that were conveniently available. 

 KirchhofP's maps and tables, besides their partial incompleteness, were not 

 suited for night work when the sun could not be simultaneously observed. 



The author adopts the lines of the spectrum of common air as the fiducial 

 points of a standard scale to which the spectra of the elements are referred. 

 The air-spectrum has the advantage of being always visible with the 

 spectra of the metals without increased complication of apparatus. 



The observations were made with a spectroscope of six prisms of heavy 

 glass of large size. The total deviation of the light with this train of 

 prisms is for the D ray about 198°. The telescope and the coUimator 

 have both an aperture of 1'7 inch. The focal length of the telescope is 

 16*5 inches. The measures were partly taken from the readings of a 

 finely divided arc of brass, which the arm carrying the telescope traverses, 

 and partly from the readings of a wire micrometer attached to the eye-end 

 of the telescope. The scale of measurement adopted gives five divisions 

 for the interval between the components of the double line D. The 

 excellent performance of this instrument is shown by the great distinctness 

 of the finer lines of the solar spectrum. All those mapped by Kirchhoff 

 are seen, and many others in addition to these. 



The spark of an induction coil was employed, into the secondary circuit 



VOL. XIII. E 



