176 PROCEEDINGS OF THE AMERICAN ACADEMY 



July and one in August, are here neglected. For Weber, Group 1 

 comprises May and December; Group 2, January and April; Group 3, 

 February and March. The form of Table XXVII. is the same as 

 that of Table XXIII. ; while Table XXVIII. resembles Table XXV., 

 but gives the number of observations separately for " axis " and " ex- 

 tent," for " displacement " and " contraction." The reason for this 

 has already been given in describing Tables XXI. and XXII. 



Tables XXIX. to XXXII. inclusive refer to the observations of 

 Eylert and Neuraayer, combined in a single grouping, since Neu- 

 mayer's four observations are not sullicient for a separate discussion. 

 The groups are as follows : Group 1 contains the observations num- 

 bered 273, 274, 290, 291, 292, in Table XI. ; Group 2 contains Nos. 

 287, 288, 289 ; Group 3, Nos. 275, 270, 277, 285, 286, 295, 296 ; 

 Group 4, Nos. 278 to 284 inclusive, and Nos. 293, 294. The form 

 of Table XXIX. agrees with that of Table XXIII. Table XXX. 

 contains a few means from observations not detailed in Table XI. for 

 want of space. These include four observations of the elongation of 

 the vertex of an " inner cone," and four observations of the boundaries 

 at elongations greater than 90°. The second and third columns of 

 Table XXX. are filled by the latitude of the observer according to 

 the mean of all the observations belonging to the group, and by the 

 zenith distance of the Sun from the data in the second and third col- 

 umns of Table XXIX. The form of Table XXXI. is that of T;.ble 

 XXV., and Table XXXII. gives similar data for the observations at 

 extreme elongations just mentioned. 



In Tables XXXIII. and XXXIV. the observations of Table XII. 

 are grouped as follows : Group 1 contains Nos. 1, 2, 8, 11 ; Group 2, 

 Nos. 3, 4, 5, 6, 7, 9, 10, 12, 32, 33, 37 ; Group 3, Nos. 13 to 25 in- 

 clusive, and Nos. 28, 36 ; Group 4, Nos. 20, 27, 29, 30, 31, 34, 35. 

 Table XXXIII. bus nearly the form of Table XXIII., with the addi- 

 tion of a section for observations at the elongation 120°. The second 

 and fifth columns give the latitude of the observer and the zenith dis- 

 tance of the Sun ; while the third and fourth give the inclination of the 

 ecliptic and the elongation of the zenith. Table XXXIV. gives data 

 corresponding to those of Table XXV., but extending, as in Table 

 XXXIII., to the elongation 120°. 



Table XXXV. gives the relative amount of atmospheric absorption, 

 expressed in terms of stellar magnitude, for different zenith distances. 

 It is derived from Miiller's table (p. 59 of his Photometrische Unter- 

 suchungen). At zenith distances less than 17°, the absorption is less 

 than five thousandths of a magnitude iu excess of its value at the 

 zenith. 



