fOi Mr. WILLARD on the Longitude 
aided by the diftindnefs of his telefcope, becaufe the fun Was 
-very near the horizon with you, while with us the altitude 
was great, and the atmofphere exceeding clear. Taking the 
mean between the deduction made from the observation's of the 
internal contad-of Venus, and -of t-he beginning and ending of 
the above fiolar eclipfe, the difference of meridians between 
'•Greenwich and Cambridge is 4I1. 44 ry"-. 
I find, Sir, in a letter from you to Dr. smith of Phila- 
delphia, Dec. 26, 1769, that by the obfervations of the 
eclipfes of Jupiter’s fateliites made at Norriton you deter- 
mined the difference of meridians between Greenwich and 
Norriton to be 5 h. T o' 35" . If we fubtrad 52", the 
difference of meridians between Philadelphia and Norriton s 
gotten, agreeably to your requeft, by terreffrial meafurement, 
we 'find the difference of meridians between Greenwich and 
Philadelphia to be 5 h. o' 43", which is the fame that it appears 
to be by the immerfions and emerfions of Jupiter’s fir ft fa tel- 
lire obferved at Philadelphia, corroded in the fame manner 
you corrected the obfervataons for Norriton, which is 8" 
more than Dr. Ewing’s determination. By obfervations of the 
tranfit of Mercury in 1769, made at Cambridge and Phila- 
delphia, the difference of meridians between thole two places 
appears by the external contact to be i6 / 02", by the internal 
16' 28" ; the mean -iff 30" fubtraded from 5 h. o' 43" leaves 
4 b. 44' ig" for the difference of meridians between Green- 
wich and Cambridge deduced in this way, which, though not 
dired, may yet be confidered as an evidence of fome weight to 
prove, that the ^difference is more than 4I1. 44b and that 
..4 h. 44' ty" may he very near the truth. This is the difference 
:that I at prefent take* when I make ufe of tables fitted to the 
tmeridian of Greenwich , but I fliould be dill glad of more 
$ correfponding 
