196 Gen. Roy’s Account of a 
the former convergence i' 50"!, we have 103° 2 / I2 y/ | for 
the angle that the meridian of Paris produced northward from 
M makes with the faid line ; but by the former fet of angles 
it was found to be only 103° o' 57" wherefore the difference 
is 1 ' 15". 
From M. Cassini’s book it appears, that Dunkirk is north 
from Paris 1 255 1 5.25 toifes, which make 133768 fathoms; and 
the point M being fouth from the tower of Dunkirk 331 fathoms r - 
there remains for the diifance of M northward from the Royal 
Obfervatory 133417 fathoms. Now, with this diftance as- 
radius, the value of an angle of 1' 15" is 48! fathoms, equal 
to 4" 34 ;// of longitude. Thus the point M, in head of being 
wefhvard from Dunkirk 1514 fathoms, will, by the laft fet of 
angles, only be removed from it 1 4 6 5 § fathoms: wherefore 
the difference between the mean and extreme places -of M, in 
this way of confidering it, will amount to 24 1 fathoms, about 
four times as much as that refulting from the comparifon Rated 
in the 57th page. In the parallel of Greenwich the extreme 
difference will amount to 58.4 fathoms, or about 5! feconds of 
longitude, not much more than one-third part of a fecond of 
time. 
In this fort of uncertainty, with regard to the precife point 
of interfe&ion of the meridian of the Royal Obfervatory of 
Paris with the line joining Dunkirk and Calais, the only 
thing that can be done on our part, is to confider the mean 
pofition of M as juft, that is to fay, to fuppofe it to be 1514 
fathoms weft ward from the great tower of Dunkirk, and 
having connected it with the Britifh triangles, to (hew then 
what angle its meridian will make with the line drawn from 
Dunkirk to Calais. 
Comparifon 
