i Intelligence and Miscellaneous Articles. 467 



collimator were made to fall upon a beautiful grating, ruled on 

 metal by Mr. Rutherfurd, which M. Mascart was kind enough to 

 lend me. The rays, brought to convergence by a lens, then tra- 

 versed a bisulphide-of-carbon prism, of which the edges were at 

 right angles to those of the slit and the lines of the grating, and 

 formed upon the phosphorescent substance a series of oblique 

 spectra, in which the rays of spectra of different orders were in 

 juxtaposition and not superposed. The slit was sufficiently narrow 

 to allow of distinctly seeing the principal lines of the luminous 

 spectrum ; and ou comparing the position of the lines and bands 

 in the infra-red part of the first spectrum with those of the known 

 lines in the luminous part of the spectra of second and third order, 

 their wave-length was obtained with an approximation, which 

 depended only on the accuracy of the scale-reading. 



The following Table contains the numbers obtained for the prin- 

 cipal lines and bands. These numbers appear exact to within one 

 or two millimetres, and may be substituted for those which have 

 been given in the publications of my previous researches. 



Wave-lengths of the principal lines and bands in the infra-red part 

 of the solar spectrum, expressed in raillionths of a millimetre. 

 700-4. A. 

 771. 

 783. 



791 to 796. 

 804. 



819. (Sodium). 

 830. 

 844. 



858 to 862. Corresponds to a calcium group. 

 876. 



898 to 900. (Magnesium.) 

 917 to 920. Band or group of lines. 



QKn ° n ' A'. Group of lines and bands very near to one 

 you to yoo. > .I „ 



968. J another * 



992. 

 1025. 



1069 to 1075. 



1115 to 1119. ] A". Group of two bands which appear to be 

 1132 to 1142. J those indicated by Capt. Abney as fa and <f> 2 . 

 1142. (Sodium.) 

 1200. (Magnesium,) 

 1254. 

 iru -. , nn *'" J Border distinct from 1351. Appears to 



ldo4 to 14UU. A . | be the band named ^ hj Abney> 



1440. Feeble band. 

 1510 to 1560. Group of bands. 



1800 to 1880. A", j Approximate numbers. This band has 

 [ been called £1 by Mr. Langley. 



