212 
Gen . Roy’s Account of 
Art. VI. The latitude of the point M near Dunkirk, and con fe- 
quently the dijlance between the parallels of Greenwich and M, 
deduced from the fame length of a degree perpendicular to the 
meridian . Alfa the comparifon of its length with that rf the 
meridional degree . 
Again, let us fuppofe G (Plate X. fig. 7.) to be Greenwich ; 
P r its meridian ; M the point near Dunkirk, fuppoled to be in 
the meridian of Paris; Mr a great circle palling through that 
point, and falling perpendicularly on Pr. Then, if we take 
61253! fathoms ===1°, we (hall have rM (—89674,7 fathoms) 
^ l ° 2 f 5 ° f - 37 1 and Gr ( = 25831 .43 fathoms) = 25 ' i 3 // .iy. 
Hence Pr will be 38° 56' 38^'. 1 7 ; and therefore as rad. : cofine 
Pr :: cofine rM : fine 51 0 1' 58". 5 the latitude of M ; and <i° 
28 / 4o // -5i° i y 5 8 7/ . 5 ~26 / 4i // .5 is the difference of latitude 
between Greenwich and M, or the diftance of their parallels. 
Now, as 3600" : 61253! :: 26' 4 1 /x . 5 (= i6oi" 5) : 27249.3 
fathoms; and this being added to 133409.8 fathoms, the meafured 
arc of the meridian between M and the Royal Obfervatory at 
Paris, we have 160659.1 fathoms for the length of the ter- 
reftrial arc of the meridian comprehended between the parallels 
of the two Royal Obfervatories nearly. But the length of the 
celeftial arc between them being 2 0 38' 26" would, at the 
rate of 6 1 253! fathoms to a degree, give= 1 6 1 743.3 fathoms, 
which exceeds the meafured arc by 1084,2 fathoms. Therefore 
it is fujfciently obvious , that the earth cannot be a fphere of thefe 
dimenfons ; but it mufi be an oblate fpheroid , on which a degree of 
a great circle , perpendicular to the meridian , in this way of con- 
fidering it , exceeds in length the mean degree of the meridian be- 
tween Greenwich and Paris in the proportion of 61253! to 
60842, or 4 1 1 f fathoms. 
Art. 
