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XCIII. A Letter from the Rev . Nevil Mafke- 
lyne, M.A. F.R.S. to the Rev. Thomas 
Eirch, Z). D. Secretary to the Royal So- 
ciety : containing the Refults of Obfervati- 
ons of the Lifance of the Moon from the 
Sun and fxed Stars , made in a Voyage 
from England to the If and of St. Helena, 
in order to determine the Longitude of the 
Ship , from Lime to Li?ne ; together with 
the whole Procefs of Computation ufed on 
this Occafon . 
SIR, St. Helena, Sept. 9, 1761. 
^and^M 24, 1 \Uring the courfe of my voyage 
1762. ^ LJ hom England to this place, I 
made frequent obfervations of the difiance 
of the Moon from the Sun and fixed flars, in order 
to determine our longitude : and, as from their agree- 
ment with each other, I humbly conceive it will be 
allowed, that the longitude may in general be afeer- 
tained by this method to fufficient exa&nefs for nau- 
tical purpofes, I flatter myfelf it may not be difagree- 
able to the Royal Society, if I communicate to them, 
through your hands, the refults of my obfervations. 
I fhall likewife deliver the whole procefs of compu- 
tation, which I ufe in deducing the longitude from 
an obfervation, wherein I include feveral ufeful rules 
of my own inveftigation, which, I apprehend, render 
the calculation not only much fhorter, but alfo much 
iefs intricate than it was before. 
I am, SIR, 
Your rnofl obedient, 
humble fervant, 
Nevil Mafkelyne. 
