io Mr. herschel on the Diameter and 
was certainly true to half a tenth of an inch ; nor did the 
direction of the meafure ever deviate, fo much as two inches, 
from a ft raight line. 
Diftance of the object from the eye in inches 7255,5 
Diftance of the eye from the vertex of the fpe- 
c ulum - - - 80,2 
Diftance of the vertex of the fpeculum from 
the objeft - - - 7335>7 
Diftance of the eye from the wall - 2292,35 
Diameter of the largeft paper - - ,99125 
Diameter of the fmalleft: - - ,5075 
Image of the largeft paper on the wall - 73, 
Image of the fmalleft on the fame - 37,8 
Angle fubtended by the large paper at the vertex 
of the fpeculum 2 7", 8 7 
Angle fubtended by its image on the wall, at the 
eye i° 49' 26", 4. 
Power of the telefcope deduced from the large paper 235,6 
Angle fubtended by the fmall paper at the vertex 
of the fpeculum 1 4", 2 7. 
Angle fubtended by its image on the wall, at the 
eye, 56' 40", 9, 
Power of the telefcope deduced from the fmall paper 238,3 
Mean of both experiments, as being equally good 2 37, 
Focal length of the fpeculum upon thofe objects 86,1625 
Upon Capella - - - 85,2 
And 237 diminifhed in the ratio of 85,2 to 
86,1625 g ive s 234,3 for the power of the inftru- 
ment upon the fixed ftars. 
It 
