1 1 6 Mr. Pictet’s Conjiderations on the 
comfort in their power. I may add, that none of the moun- 
tains on which I have obferved, and which are pointed out in 
the map as likely ftations, prefent any danger. 
If a furvey of that kind, executed in a mountainous coun- 
try, is liable to fome difficulties, it offers, on the other hand, 
advantages which perhaps more than overbalance thofe diffi- 
culties. 
Firft, the vifual rays being lefs interrupted, the triangles 
become larger, and the ftations fewer in number; whence the 
labour of the obfervers, and the chances of error, are by fo 
much diminifhed. 
Secondly, Thefe fame vifual rays proceeding through ftrata 
of air lefs denfe and more free from the vapours which com- 
monly thicken the lower parts of the atmofphere, the danger 
of irregular refractions is by fo much lefs, and the fignals may 
be more diftindtly perceived from great diftances. 
Befides thofe advantages which chiefly concern the meafure- 
ment itfelf, the country would offer facilities for other natural 
enquiries, not unworthy the attention of philofophical men, 
and which might eafily be united with the capital objeCt of 
thefe labours, with which objeCt fome of thefe enquiries are 
Intimately united. I range among them, 
The accurate determination of the length of the Ample pen- 
dulum, which beats feconds in this mean latitude. 
Experiments to be made on the ofcillations at different 
heights, with an invariable pendulum. 
Experiments on the lateral attra&ion of mountains repeated 
and varied. 
Obfervations on meteors, and feveral atmofpherical pheno- 
mena relative to refra&ions, to heat, to hygrometry, to electri- 
city, &c„ 
But, 
