312 PROCEEDINGS OF THE AMERICAN ACADEMY 



The observed outlines of the head of the Comet have been obtained 

 by tracing the curve of the outer edge, and the place of the nucleus, 

 upon slips of mica laid over the original drawings. The curves were 

 then collected in groups and reduced to a common scale, and finally- 

 combined in normals. On comparing the groups, it was found that 

 there was scarcely any change in the character of the apparent out- 

 line during the interval from August 24 to November 12, covered by 

 the observations. From this it would seem that there was an actual 

 change in the figure of the Comet itself, since the alteration of the in- 

 clination of the axis to the line of vision, which intervened, must other- 

 wise have occasioned a considerable variation in the apparent figure, 

 due to perspective foreshortening. 



The original number of groups was six, subsequently reduced to 

 four normals, as represented on the plate. At the date of the normal 

 for September 30, the day of perihelion passage, the apparent figure was 

 nearly that afforded by a section through the axis of the tail. 



The drawings employed were made at the following places : — ; 



Aug. 24, 31 ; Sept. 3, 23, 26, 28, 



29, 30 ; Oct. 1, 5, 6. 

 Oct. 3, 4, 7, 10, 14, 16, 18. 

 Sept. 20, 28; Oct. 4,5,7,8, 11, 



16. 

 Sept. 22, 28 ; Oct. 1, 4, 6, 9, 12. 

 Oct. 4, 10. 



Sept. 4, 11, 16, 22, 29 ; Oct. 2, 4, 

 8,9,11,13,15,17,18,19,22. 

 Oct. 12, 13, 14, 24; Nov. 7, 12. 

 Sept. 12, 16, 18,22, 24,25,30; 

 Oct. 5, 7, 8, 9, 13. 

 Cambridge, England, wt. = 2. Sept. 27, 30 ; Oct. 2, 5, 6, 8, 9, 



11, 15, 16. 

 Haddenham, England, wt. = 3. Sept. 24; Oct. 5, 8, 11, 17. 



Greenwich, England, wt. = 3. Oct. 2, 3, 4, 5, 9, 11, 15. 



Hamilton College, N. Y., wt. = 3. Oct. 7, 10, 15, 17. 

 Bradstones, Liverpool, Eng.,wt. = 3. Sept. 12; Oct. 3, 4, 5, 8. 

 Observatory of Harv. Coll., wt. = 3. Sept. 8, 20, 24, 25, 28 ; Oct. 2, 6, 



8,9,10,11,15,18,19. 

 Geneva, wt.= 2. Sept. 26 ; Oct. 3, 5, 6, 7, 9, 13, 



14, 15. 



