THERMOMETRICAL OBSERVATIONS. 219 



The arc being now extended to the weft fide of 

 Thompfon's creek, the following offsets into the parallel 

 of latitude were laid off, viz. 



Took equal altitudes of t Pegafi, to determine the direflion of our arc, 

 which at the diftance of 206 perches eafl from the tranfit, was 19.35 inches 

 fouth of the prime vertical, which fubtends an angle of 1' 40" 48"'. The 

 tranfit was 8 miles and 118 perches eaft from its fecond ftation, which 

 diftance fliould have given an angle of i' 44'' 52"', hence it appears, that 

 the arc was diredled too far north by 4" 4'" on a fuppofition that this was 

 gradually accumulating, the tranfit was too far north by 6.8 inches, which 

 is accounted for in the offsets for the 19th, 20th, and 2 ift miles. 



27th. Re-examined the direcflion of our arc by taking equal al- 

 titudes of the fame ftar, the coincidence was lefs than li" 

 which was probably occafioned by an impeifeflion infepa- 

 rable from obfervations : this fmall difference was bifefleJ 

 and the diftance of 20.8 inches was laid off from the point 

 of bifeiflion to the fouth, and the arc continued through its 

 termination as in the former cafes, 



29th. Clock ran down in the night. 



30th. Wound up the clock and fet it a-going. 



0£t 7 th Equal altitudes of the Sun. 



' ' ' A. M. 8*' 36' 1". r. M. 3" 21' 44". 



I Qth. Equal altitudes of the Sun. 



^ A.M. S*" 27' 29". P.M. 3" i7' 50", 



Immerfion of the ift fatellite of If. obferved at 10'' 55' 31'' 

 do. . 2d . do. . 13 21 15 



Night very fine, belts diftinft, magnifying power 120. 



20th. 



