the Trigonometrical Operation. 22 r 
by two fets of angles given in the Meridienne venfee, as adverted 
to in the Paper of 1787, Phil.Tranf. Vol. LXXVII. p. 195, 196. 
Art. XII. The longitudes of Dunkirk and Paris , eafward from 
Greenwich , determined by the fum of four differences of me- 
ridians. 
In fig. 9. let PA be the meridian of Greenwich ; G Goud- 
hurft, PR its meridian ; T the Ration at FolkRone Turnpike, 
PS its meridian ; C Calais, PC its meridian ; D Dun- 
kirk, and PB its meridian. Alfo, let AG, RT, SC, and BC, be 
arcs of great circles, making the angles PAG, PRT, PSC, 
and PBC, right ones. 
The angle at GoudhurR, between its meridian and Tenter- 
den, is 107 26 40 .3 > hence, by drawing parallels to this 
meridian through Tenterden and the Ration at Allington Knoll 
(fee the plan of the triangles) we fliall get 946.6 fathoms for 
what the Ration at the Turnpike is fouthward, and 28098.8 fa- 
thoms for what it is eaflward from the meridian of GoudhurR. 
Now, 60859.4 fathoms being nearly = T of the meridian in the 
latitude of GoudhurR, we have 946.6 fathoms = 56" nearly za 
the arc GR; and the latitude of GoudhurR being 51° 6' 49 // .'6 s 
that of the point R is 51° 5' 53". 6 ; hence the co-latitude RP 
= 38 54‘ ! 6 // .4: and fince the degree of a great circle, per- 
pendicular to the meridian, in this latitude has been fhewn to 
contain 61248 fathoms nearly; therefore RT= 28098.8 fa- 
thoms will be 27' 31 // . 6 . This arc and RP give the angle 
RPS = o° 43' 49C86 for the difference between the meridians of 
GoudhurR and FolkRone Turnpike. 
The angle at FolkRone Turnpike between its meridian and 
Dover was obferved 66° 48' 35", and if we draw a parallel to 
this meridian through Dover, we fhall find, that Calais is 
25284.2 
