[ 6 °7 ] 
XCIX. ExtraB of a letter from M. de la 
Lande, of the Royal Academy of Science ; 
at Paris, to the Rev. Mr . Nevil Mafkelyne, 
F.R. S. dated Paris, Nov. 18, 1762 *. 
S I R, 
Read Nov. 25, IT AM glad that you have proved, from 
1762. y 0ur own experience, the exadtnefs 
of the obfervations of the diftance of the moon from 
ftars for finding the longitude at fea, as M. de la 
Caille had done in 1753. I am as fully convinced 
as you can be of thefe advantages, and am not a lit- 
tle pleafed to learn that you are about printing a con- 
cife method of computing the corrections of re- 
fraction and parallax. 
In the feCtor, which our members of the acade- 
my carried with them to the north, the plumb-line 
* This letter I received from M. De la Lande in ar.fwer to 
one I had wrote to him, “ in which I propofed to him, to 
« make obfervations at Paris, in correfpondence with others 
« made here, of ocultations of fixed ftars by the moon ; in 
“ order to determine the exa£t difference of longitude betwixt 
“ London, Paris, and Greenwich : which is not yet certainly 
“ known with that accuracy which the nicety of modern aftro- 
“ nomy feems to require ; and at the fame time defired him to 
« look out for the mod convenient opportunities for this pur- 
« pofe, by means of the calculations contained in the French 
“ almanack, called the Connoifiance des Temps, of which he 
<l is the editor.” 
Nevil Mafkelyne. 
Vol. LII. 
defeends 
