[ 57 * ] 
muft fhew the difference of longitude between that 
meridian and Greenwich. 
Perhaps the following method of deducing the 
longitude from the obfervations may be leaft liable 
to miftake : 
Find what the longitude by account was, at the 
inftant of taking the Sun’s or ftar’s altitude, for the 
regulation of the watch ; which being turned into 
time, at the rate of one hour for every 15 0 , and four 
minutes for every degree, add to the correct time 
from noon, when the diffance of the ftar from the 
Moon was taken, if the fihip is to the weft of Green- 
wich, or fubtrad: from it, if it be to the eaft : this gives 
the apparent time at Greenwich by account ; and the 
mean time is found, by applying the equation of 
time ; to which time, compute the Moon’s longitude 
and latitude from the tables, and the diftance of the ftar 
from the Moon, by the rules, and find, by propor- 
tion, as before, what time the Moon will take to run 
over the difference between the diftance computed, 
and that refulting from the obfervation ; this turned 
into degrees and minutes of the equator, will fihew 
the error of the fhip’s account; and the following- 
rules will fihow, whether the fihip is to the eaft or welt 
of its account : 
If the diftance of the Moon obferved eaft of a ftar 
(or the Sun in the firft quarter) is greater than that 
computed, the fihip is weft of the longitude by ac- 
count ; but if the diftance obferved is lefs than that, 
computed, it is eaft of account. 
If the diftance of the Moon obferved weft of a ftar 
(or the Sun in the laft quarter) is greater than com- 
puted, the ftfip is eaft of account j but if the diftance 
obferved 
