Convenience of a Meafurement near Geneva. 1 1 y 
But, above all, the improvement of barometrical meafure- 
ments- would moftly deferve the attention of theCommiffioners. 
Nothing, as it feems, is now wanting in the theory of the 
operation ; and it is only from a number of a&ual obfervations, 
made at different heights, and with every due precaution, 
compared with geometrical meafurement, that the co- efficient 
(either conftant or variable) to be applied as a correction for the 
atmofpherical heat, will be obtained. That refearch muft be 
merely empirical; the effedt fought for being the refult of 
many complicated caufes, fome of which are yet unknown. 
The real height of every ftation being well determined, the 
time to be fpent there for other purpofes would allow a num- 
ber of barometrical obfervations in varied circumftances ; and 
from thefe obfervations, rightly compared between themfelves, 
interefting and ufeful refults may juftly be expe&ed. 
I have the honour to be, &c. 
MARK AUGUSTE PICTET* 
Geneva* 0&. 30, 1790, 
E clair cijfernmz 
