Z !% I 
l o,n d. Thefe allowances were accordingly made 
in deducing all the differences of meridians ex^'. 
preffed in the laff. column of the foregoing table. 
The obfervations made at Greenwich, oppofed tor , 
thqfe made in north America, are either corre--.- 
lpondingones, which however is very feldom the cafe v , 
or elfe. the neareft to them that were obferved. The l < 
error of the computed time of the eclipfe in the ^ 
Nautical Almanac was faund.by- the neareft obfer- 
vation at Greenwich, and the time of the Nautical' 
Almanac, thus corrected, compared with the time* 
obferved in Nor»th America, gave the difference off 
meridians between the-p'ace and Greenwich ; farther 
redu&ion being firft made for the difference of 
teiefcopes, if neceffary, in the manner already ex-., 
plained. It is however to be underftood, that, in 
this way of deducing the difference of meridians, 
by comparing an eclipfe obferved at Greenwich 
with another eclipfe obferved elfewhere, the inter- 
val of time between the two eclipfes ought to be 
very fhort $ otherwife it cannot be fuppofed, 
that the errors of the tables fhould continue the 
fame. Hence it has happened, that many of the 
North American obfervations have been loft: for 
this ufe, for want of obfervations near enough 
to them made at Greenwich. In fome other cafes, 
indeed, I have been obliged to compare together 
obfervations made with a greater interval between 
them than I fhould have chofen, but for fear of 
lofing fome ufeful comparifons. As the preceding 
table affords feveral determinations of the longitude 
of moft of the places, it may be proper to point 
out, how the true difference of meridians may be 
B b 2 beft 
