594 2®\ willard on the Longitude 
aided by the diftin&nefs of his teiefcope, 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 obfervations of the 
internal contact of Venus, and of the beginning and ending of 
the above .Tolar eclipfe, the difference of meridians between 
‘Greenwich. and Cambridge is 4 h. 44/ 1 7". 
1 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 fatellites made at Norriton you deter- 
mined the difference of meridians between Greemvich and 
Norriton to be 5 b. i' o' 35". If we fub tract 52", the 
-difference of meridians between Philadelphia and Norriton, 
gotten, agreeably to your requeft, by terreftrial 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 firft fatel- 
■lite ohferved at Philadelphia, corrected in the fame manner 
you corrected the obfervations for Norriton, which is 8" 
more than Dr. Lwin-g’s determination. By obfervations of the 
tranfit of Mercury in 1769, made at Cambridge and Phila- 
delphia, the difference of meridians between thofe two places 
appears by the external contaff to be 1 6' 02", by the internal 
16' 28" ; the mean 16' 30^ fubtradled from 5 h. o' 43" leaves 
4 b. 44' 13" for the difference of meridians between Green- 
wich and Cambridge deduced in this way, which, though not 
-diredt, may yet be cenfidered as an evidence of Tome weight to 
prove, that the difference is more than 4I1. 44', and that 
4I1. 44' 17" may bewery near the truth. This is the difference 
rthat I at prefent take* when I make ufe of tables fitted to the 
rmeridian of Greenwich] but I fhould be flill glad of more 
1 correfponding 
