propofed trigonometrical Operation. 207 
abfurd, it has been judged beft to take a mean between them 
for a mean latitude. In like manner the latitudes of the two 
Italian degrees differing but little from each other, a mean 
length has been taken between them for a mean latitude. Ac- 
cordingly the latitudes and the meafured lengths of the degrees 
which, in the fecond ellipfoid, have been compared together, 
will appear as underneath : 
Obfervers names. 
Countries. 
Latitudes. 
Meafured lengths. 
Bouguer, 
Peru, - 
- 
O 
O 
/ 
0 
— 
60484.5 
Mason and Dixon, 
Maryland, 
— 
39 
12 
— 
60628.5 
Boscowich, 
Beccari A, 
Italy, 
Piedmont — 
43 ° 0' 1 
44 44 J 
i 43 
H 
1 60725.5 i 
L 60821.3 j 
J, 60773.4 
Cassini, &c. 
Middle of France, 
— 
45 
0 
— 
60777.6 
Liesganig, 
Cassini, &c. 
Auftria, — 
North of France, 
48 43 1 
- 49 2 oJ 
>49 
3 { 
'60839.43 
_ 60826.6 J 
>60833.0 
Maupertuis, &c. 
Lapland, 
— 
66 
20 
— 
6H94.3 
Now thefe fix degrees, being fucccfiively compared with 
each other, fifteen refults are thereby obtained, whereof the 
arithmetical mean gives for the ratio of the femi* diameters of 
the ellipfoid that of 192.483 to 191.483. By adverting to the 
table, it will further appear, that the arc MP Ihould be in 
length 27331 fathoms. The arc M Perpignan exceeds the 
truth 1758, the 45th of latitude 180, and that at the polar 
circle near 88 fathoms. 
The ratio of the femi-diameters of the third ellipfoid 216.06 
to 215.06 is obtained by adhering to the meafured lengths of 
the degrees at the equator and polar circle. According to this 
hypothefis the arc MP fhould contain 27301 fathoms. The 
arc M Perpignan exceeds the truth 1288, and that at the 45th 
of latitude more than 128 fathoms* 
The 
