194 Gen, Roy 4 s Account of a 
In like manner the diftance from Greenwich to P, on the 
parallel of Greenwich, will then be readily computed, anfwer- 
ing to the difference of longitude between the two Obferva- 
tories ; which, as far as can be judged from the map of Kent, 
corrected for the error in the direction of its meridian, amounts 
to about 2° 29' 20 y/ , fuppofing always that no uncertainty 
remains with regard to the pofition of the point M. But here 
fome remarks become neceflary, which may probably fuggeft 
to the Academy of Sciences, that a further inveftigation of 
this matter may be needful on their part. 
By referring to the 57th page of the firft part of M. Cas- 
sini’s Book (La Meridienne verified), it will be feen, that Dun- 
kirk, by one feries of triangles, is eaftward from the meridian 
of Paris 1426.53, and by another 1414.29 toifes, whereof the 
mean is 1420. 41, equal to 1514 fathoms. This difference of 6§ 
fathoms, or little more than half a fecond of longitude between 
the mean and extreme places of M, is certainly very inconti- 
derable. But in the 60th page, where, in verifying the meri- 
dian of Paris, by the comparifon of the angle that Broulezele 
makes with the meridian of Dunkirk, and the angle of con- 
vergence of one meridian to the other, a difference of 2 1 fe- 
conds between io° 16' 13" and io° 16' 34", is alledged to bs 
almoft infentible, we do not think to' be a conclution fo unex- 
ceptionable. This, however, is not the only caufe of uncer- 
tainty with regard to the juft polition of the point M : one of 
more importance arifes, from the difference that is found by 
two fets of triangles in the angle of interfe&ion of the meri- 
dian of Paris, with a line drawn through M from the tower 
of Dunkirk to that of Calais. 
Thus, by p. 53. and 56. of the firft part of M. Cassini’s 
^ook, Dunkirk being the ftation, Broulezele makes an angle 
with 
