i io Mr. Pictet’s Confederations on the 
It is obfervable, on the infpeCtion of the map, that the 
chain of triangles lies moftly on the weft fide of the meridian 
line. I was forced to difpofe it thus, to be within reach of the 
only place where a convenient bafis could be found, viz. the 
marfiies of Choutagne. I have feen this place, and am well 
allured, that the meafurement in a convenient feafoti would be 
attended with no difficulty. The difpofition and proportion of 
the bafis of about 29,000 feet traced on the map, are the refult 
of operations I have made on the fpot. 
The fouthern part of the meridian line, vifible from the 
Obfervatory of Geneva, pafles over the fummit of a mountain 
called Mount Saleve , where we have a meridian mark, at the 
diftance of about 5600 toifes, and at the height of about 500 
toifes above the level of the lake. I have obferved from that 
fummit, that the fame line protracted fouthwards is not inter- 
cepted by the mountains but at a great diftance, and in a place 
which, as far as I could judge, muft be near the fouthern end 
of the arch. I am ignorant if that place is acceftible ; but if 
it fhould happen to be fo, it would be a fortunate circumftance, 
inafmuch as it would offer a very fimple, quick, and accurate 
verification of the direction of the meridian line refulting from 
the chain of triangles, by actually protraCting the vifual line 
given immediately by the tranfit inftrument of the Obferva- 
tory down to the end of the arch, by the help of two inter- 
mediate ftations only. I do not believe that fuch a verification 
has ever yet been praCtifed. 
We fee hitherto no local difficulties in the meafurement of 
an arch of about 84 minutes of the meridian of Geneva. The 
meafurement of the parallel of longitude, eaftwards of the fame 
^place, feems to be of a flill eafier execution, iiifomuch that I 
1 believe 
