ASTRONOMY. 215 



Holden. A thorough optical examination of the comet's spectrum lias 

 been niade bj' Young, Harkness, and Pickering. The spectrum has 

 been photographed by Draper and Huggins. The light of difterent 

 parts of the comet lias been i>hotometrically determined by Pickering, 

 the results being expressed in stellar magnitudes on Pogson's logarith- 

 mic scale, showing the comet to be of the seventh magnitude very near 

 the nucleus, and the tail, at 49 from the nucleus, to be of the 11.0 

 magnitude. And, lastly, the polarization of the comet's light has been 

 observed by Wright, establishing the fact that the light emitted by the 

 tail is polarized rather strongly in a plane passing through the sun's 

 place, the percentages indicating that reflected sunlight constitutes the 

 greater part of the light of the tail. 



Professor Stone and his assistant, of the observatory at Cincinnati, 

 saw this comet "separate before their eyes, forming a double comet." 

 It is well known that Biela's comet did separate, but no observer actu- 

 ally saw the process, which, it is safe to say, must have been very 

 gradual. 



The observations of Professor Stone were doubted by Mr. Rock at 

 the Kaval Observatory at Washington, who was observing the comet 

 at the same time, and the question was unsettled for the time. 



It has since appeared that Mr. Wendell, of Harvard College Ob- 

 servatory, saw the nucleus double on one occasion, and at the Wash- 

 burn Observatory the nucleus was seen double on several nights, by 

 Professor Holden and Mr. Burnham, and on one night a perfectly satis- 

 factory measure of the two parts was made by Mr. Burnham. 



From a note furnished to the Harvard College Library Bulletin, by 

 tbe observatory, the following is extracted: 



"Much attention has been paid to cometary astronomy during the 

 past summer at the observatory by Messrs. S. C. Chandler, jr., and O. 

 C. Wendell. Orbits and ephemerides for four of the comets of the year 

 have been computed within a few days of their discovery in the north- 

 ern hemisphere, and circulated among astronomers by means of the 

 telegraphic cipher devised by Messrs. Chandler and Eitchie. These 

 results were largely derived from the observations of position made at 

 the observatory. Professor Pickering has made many photometric 

 observations of the brighter comets of the year. 



"The spectrum of Comet B (the great comet which appeared towards 

 the end of June) was shown by European observations to contain tive 

 bands, three of which are familiar in cometary spectra, while the other 

 two seemed new. It appears probable that these two are identical with 

 two of the three bands found last winter, at the observatory, in the 

 ])eculiar si)ectrum of a star in Canis Major, LI. 13,412, the third band 

 being apparently due to hydrogen. An interesting analogy between 

 the spectra of comets and stars is greatly strengthened by this observa- 

 tion, since the three familiar bands of cometary spectra Avere previously 

 taken to agree witb the bands seen in tbe spectra of a small class of 

 stais, designated by Secchi as stars of the fourth type." 



