172 Prof. C. Pritchard. On the Capacities of tico [May 3, 



and the light was re-determined by the same method, and the same 

 stars, on March 3rd, 1888, the weather admitting of no earlier trial. 

 Result : — 



Light reflected by T ^%-inch mirror _ 

 Light transmitted by 12^-inch refractor — 



Light reflected by y^-inch mirror 



' Light transmitted by 4-inch refractor 



The Mirror. 



Determination by the process explained above, on January 3rd, 

 1888, of the light reflected by the -|~§-inch mirror. Result : — 



y Light reflected by the ^|-inch mirror I' 23 



Light transmitted by the 12^-inch refractor 



yj Light reflected by the ||-inch mirror _ 

 Light transmitted by the 4-inch refractor 



This mirror was re-silvered at the Observatory by Mr. Jenkins on 

 January 9th, 1888, and re-examined on January 17th, 1888. With 

 the results — 



y-j-j Light reflected by i4 _ i ncn mirror _ -^.gg 

 'Light transmitted by 12^- inch refractor 



VIII I^ghfc reflected by |-^-inch mirror _ ^q.^q 

 Light transmitted by 4- inch refractor 



On combining the above results, it appears that by means of the 

 comparisons with the 12^-inch refractor — 



j-^r Light of -i^-inch mirror re-silvered _ 1*33 \-QQ 



Light of -|-f-inch mirror after 9 months' use 1*23 



and from comparison made with the 4-inch refractor — 



2£ Light of -§-f-inch re-silvered 10*7 _ -^.Q7 



Light of -|-§-inch mirror after 9 months' use 10 



In like manner, from similar processes with respect to the -j^-inch 

 mirror, it appears that when the comparisons were made by the aid 

 of the 12^-inch refractor — 



Light of y^Q-inch mirror re-silvered _ 120 -^.q^ 



Light of yV^-inch mirror after 9 months' use 118 

 and when compared by means of the 4-inch refractor — 



2Qj Light of y^p-inch mirror re-silvered 9*72 _ -^.^g 



Light of yYo-inch mirror after 9 months' use 9'15 

 The approximate identity of the above results is, I think, such as 

 to coimnend the method adopted with the wedge photometer to con- 



