THE APPAREXT POSITIOX OF THE ZODIACAL LIGHT. 



137 



the latitude of the boundaries of the "Stronger Light" at the elongation 60° 

 should be omitted, as not determinable from the sketch. Under the date of 

 July 15, 1854, the last result for the latitude of the boundaries of the " Stronger 

 Light" at 60' should also be omitted. Under the date of Aug. 17, 1854, column 

 "/," the last result, 18, should be 13. 



The required data for the morning observations of Jones at the elongation 

 60' were obtained from his work by the method previously emploj-ed;^ but the 

 longitude of the sun was referred to a date one day earlier than that given b}' 

 Jones, who employs civil time, so that the same longitude might be retained for 

 all observations belonging to the same night, whether made early or late. This 

 precaution, however, is of no practical importance, and might have been neglected 

 without noticeably affecting the results, since a single degree is a relatively small 

 quantity in the data here collected, and given below in Table I., the headings of 

 which have the same meaning as those corresponding to them in Table X., already 

 mentioned. An additional column in the present table gives the excess of absorp- 

 tion at the southern over that at the northern boundary, computed in terms of 

 stellar magnitude by means of an auxiliary chart and the tables given in my 

 former communication. As previously, negative quantities are indicated by Italic 



figures. 



TABLE I. 



Morning Observations by Jones : Stronger Lirjht : Elongation 60°. 



VOL. XL 



1 Free. Am. Acid. XIX. 171. 



18 



