Trans. N. V. Ac. Scz. 20 Oci. 30, 



Young, at Princeton, has sent me a letter from which I obtain the fol- 

 lowing data : 



" The weather has been so bad here that we have been able to make 

 but few observations of the comet. 



" I send a note, from the Stderial Messenger, of observations made here 

 on the 19th and 23th of September. It has since been observed at 

 the Halsted Observatory (with the 23-inch telescope) on October 2, 4 

 and 15 {civil time'), and at the S. S. Observatory with the 9>^ tele- 

 scope, on the loth and 24th. 



" On the 2d, the Spectrum showed very plainly the D lines in addition 

 to the usual cometary (carbon) bands.* There was no sensible dis- 

 placement due to motion. In the middle carbon band (near (^), the 

 three bright lines, observed in the comet of 1881, came out finely. No 

 dark lines could be seen, though there was a pretty strong continuous 

 spectrum from the nucleus of the comet. 



" On the 4th, the D lines were barely visible, and since then the spec- 

 trum has been simply that ordinarily shown by comets. The three 

 bands have been visible in the spectrum of the tail to a considerable 

 distance from the head. This I mention in opposition to the statement 

 (which I think a mistake) that the spectrum of the tail is simply con- 

 tinuous. 



" In the Telescope — On the 2d, the nucleus was elliptical, about 4" by 

 8". There was one well-formed parabolic envelope, and there was a 

 dark streak following the nucleus. The edges of the streak were 

 nearly parallel, pretty well defined, and it could be followed for about 

 20', till it lost itself in the tail. 



"On the 4th, the nucleus had become much elongated —something 

 like an Indian club in form — large end towards the sun. The envelope 

 had lost all definiteness of outline. The dark stripe beyond the nu- 

 cleus was very faint, and along the northern edge of it there was a 

 bright streak. 



" On the loth, the nucleus had assumed the appearance it has since 

 retained, consisting of a spindle-shaped, slightly curved, nebulous 

 streak of light, with five or six knots or centres of brightness scattered 

 through it. The brightest of these knots (perhaps the true nucleus) 



* In the Dun Echt circular No. 56, sent from Lord Crawford's Observatory, England, we 

 read: " The spectrum of the nucleus continuous, with many bright lines, of which D is 

 ty far the brightest ; all the bright lines displaced towards tne red by about one-eighth of 

 the interval of the D lines.'' This separation would correspond to a motion of reci-ssion of 

 about twenty miles per second. Prof. Voung's observation was made after the comet had 

 passed perihelion ; so also were the observations made at Dun Echt. The date of the Dun 

 Echt observations was September 18. If a displacement showing motion really occurred, it 

 will be the first time that such a phenomenon has been noted with reference to a comet. 

 The observation IS one of such delicacy that we must wait further corroboration beforeac- 

 <;epting the Dun Echt observation, especially as Prof. Young has not been able to discover 

 any sensible displacement. 



