Convenience of a Meafurement near Geneva. icq 
mined. The mountains and lines drawn in black, on the map fub- 
loined (Tab.ll.), fliew thefftations and triangles already obferved ; 
thofe in red * are only p relumed, but their places will probably” 
differ little in reality from thofe which are there indicated. The 
map, as to the filiation of mountains, has no pretenfions* but 
to fuch an exa&nefs as may refult from angles obferved with a 
Hadley’s fextant, without a reduction to the horizon ; but 
the fituation and figure of our lake is exactly true, being the 
refult of a minute and accurate furvey taken by the late Pro- 
feflbr Mallet and myfelf. 
The vifible part of the meridian of Geneva is foon termi- 
nated northwards by the fir ft chain of Mount Jura; but the 
country opens to the N.N..E. and the northern ftation might be 
eafily chofen in fome place of the Pays de Vaud , vifible from 
the Obfervatory of Geneva, and which could be determined 
by only one additional triangle, I take the liberty to point out 
two fuch places. The one, called Vincy , about 16 minutes 
north of Geneva, and where the circumftance of my poffeffing 
a country houie would facilitate the difpofitions neceffary for 
the aftronomical obfervations. The other place is the top of a 
mountain, called the Dent de Vaulion , making part of the chain 
of Mount Jura, and where an occafional obfervatory might be 
eredted without much difficulty : it is 10 minutes north of 
Vincy, or 26' of Geneva. The whole arch from St. fean de Mau~ 
rienne to this laft place would be about 1 degree 24 minutes. 
The cekftial obfervations might perhaps be made in the four 
places above mentioned ; and the meridian arch would be thus 
obtained in three portions, whofe comparifon with the ter- 
reftrial fedtions, meafured geometrically, would be a proof of 
the accuracy of the operation. 
* In the engraving of this map, dotted lines are employed, to exprefs what- 
ever was drawn with red in the original. 
It 
