1868.] Mr. W. Huggins on the Spectrum of Cornet II., 1868. ; 481 



the whole survey, and is accompanied by three maps, which have been 

 prepared, with the permission of the Hydrographer, Captain Richards, 

 R.N., F.R.S., under the careful superintendence of the Assistant Hydro- 

 grapher, Captain Frederick John Evans, R.N., F.R.S., one map being 

 allotted to each of the three magnetic elements, viz. the Declination, In- 

 clination, and Intensity of the Magnetic Force. In these maps the Isogo- 

 nic, Isoclinal, and Isodynamic lines have been drawn, by the author of the 

 paper, conformably with the observations around the circumference of the 

 globe between the parallel of 30° S. and the South Pole. The paper also 

 contains Tables, prepared with a view to the revision of the calculations of 

 Gauss's ' Allgemeine Theorie des Erdmagnetismus.' They give the values of 

 each of the three magnetic elements at the intersections of every fifth de- 

 gree of latitude between 40° of south latitude and the South Pole, and 

 every tenth degree of longitude between and 360°. 



" On the Spectrum of Comet II., 1868.'' By William Huggins, 

 r.R.S. Received July 2, 1868. 



(Abstract.) 



The author describes the appearance of the comet in the telescope on 

 June 22 to consist of a nearly circular coma, which became rather suddenly 

 brighter towards the centre, where there was a nearly round spot of light. 

 A tail was traced for nearly a degree. 



He found the light of the comet, when examined with a spectroscope, 

 furnished with two prisms of 60°, to be resolved into three broad bright 

 bands. 



The brightest band commences at about h, and extends nearly to F. 

 Another band begins at a distance beyond F, rather greater than half the 

 interval between h and F. The third band occurs about midway between 

 D and E. In the two more refrangible of these bands the light was brightest 

 at the less refrangible end, and gradually diminished towards the other 

 limit of the bands. The least refrangible of the three bands did not exhi- 

 bit a similar gradation of brightness. 



These bands could not be resolved into lines, nor was any light seen 

 beyond the bands towards the violet and the red. 



The measures of these bands are given, and a diagram of their appear- 

 ance. 



The author found this cometic spectrum to agree exactly with a form of 

 the spectrum of carbon which he had observed and measured in 1864. 

 When an induction spark, with Leyden jars intercalated, is taken in a 

 current of olefiant gas, the highly heated vapour of carbon exhibits a spec- 

 trum which is somewhat modified from that which may be regarded as 

 typical of carbon. The hght is of the same Tcfrangibilitics, but the sepa- 

 rate strong lines are not to be distinguished. The shading, composed of 



