20 6 Gen. Roy’s Account of a 
ratio of the femi-diameters formerly mentioned 1 79.047 to 
178.047. On this hypothefis the arc MP fhould contain 
27350 fathoms. The error on the total arc M Perpignan 
amounts to 2078 fathoms. M. Bouguer’s degree at the equa- 
tor being adhered to, the 45th of latitude will exceed the truth 
216, and that at the equator 148 fathoms, 
The ratio of the femi-diameters of the fecond ellipfoid, 
which comes now to be fpoken of, has been obtained by the 
comparifon of fuch meafured lengths of the degrees of the 
meridian in different latitudes, as have been found to be moft 
confident with each other. Our countryman, Mr. Norwood, 
was the firff, of late times, who made any attempt of this 
fort. But the meafurement, executed by him in the year 
1633, between London and York, has no pretence to exa£l- 
nefs, ftnce he himfelf tells us, that 'when he did not meafure , he 
paced l Befides, his degree is as great, or even greater, than 
that in Lapland ; and thefe are furely fufficient reafons for 
rejecting it from the comparifon. The degree meafured by M. 
Liesganig in latitude 45 0 57% in that part of Poland lately- 
fallen to the fhare of the Emperor and annexed to Hungary, 
being fo much Ihorter than degrees to the fouthward of it, 
gives grounds to fufpecff, that fome error had crept into that 
operation, or that the plummet had been affedled by the attrac- 
tion of neighbouring mountains, and therefore is not made 
ufe of on the prefent occahon. M. de la Caille’s degree at 
the Cape of Good Hope, being in fouth latitude, and fo much 
greater than thofe of the fame height in northern latitudes, 
is improper likewife to be brought into the comparifon, 
left the difference may have arifen from a diflimilarity in the 
two polar fides of the ellipfoid. The degree meafured in the 
north of France, compared with that in Auftria, coming out 
abfurd, 
