[ i6o ] 
lefs than 9' 25". If we compare the obfervations 
made at Savile-houfe with the fame obfervation by 
M. de la Lande at Paris, and reafon in the fame 
manner, we fhall find that the difference of longi- 
tude between Greenwich and Paris muff be lefs than 
9 / 33 / - Thus far, therefore, a limit, oneway, is 
fixed for the difference of longitude between thefe 
two places. 
The late tranfit of Venus was the only one which 
had ever been obferved at Greenwich and Paris, and 
by comparing the obfervation at Greenwich, with 
that made by M. de la Lande at Paris, the difference 
of longitude comes out — g' and if we compare 
the obfervations at Savile-houfe (3c/ 7 of time weft of 
Greenwich) with that of M. de la Lande *, the faid 
difference of longitude comes out = 9' 16". Since, 
therefore, we have only this one tranfit of Venus, 
by which we can determine this difference of lon- 
gitude, we mu ft have recourfe to the tranfits of Mer- 
cury, of which there have been four fince the year 
1723, obferved at London, at Greenwich and at 
* M. de la Lande faw the internal contact 
nus with the Sun’s limb 
Pere Clouet 
M. Meffier » 
M. Ferner — — 
M. de la Caille 
M. Maraldi - 
Since, therefore, the obfervations of meflieurs Maraldi and de 
la Caille differ fo much from the obfervations of the firft four 
gentlemen (who agree very nearly together) it is plain that they 
ought to be rejected ; and indeed M. de la Caille fays, in a letter 
to Dr. Bevis, that the telefcope he obferved with was a bad 
one, and confequently his obfervation not to be depended on : 
M. de la Lande fays the lame in a letter to Mr. Mafkelyne, read 
at the Royal Society. 
Paris. 
