736 Col. roy’s Experiments for 
circumftances from thofe on Saleve, and require a greater 
equation, it is unneceffary to enter into any minute com- 
parifon of the two fets : neverthelefs, that fome idea may 
he formed of the caufe, of part at leaft, of the difference 
that takes place between them, I have colle&ed into one 
view, the computations of fuch as were made in extreme 
temperatures ; namely, the coldeft of thofe at Sun-riling 
(though the whole of that clafs were conlidered as ex- 
ceptions from the rule) the coldeft and hotteft of the 
ordinary obfervations ; alfo thofe on the Dole r/ ', at Genoa, 
and at Turin, whereby the heights of the lake of Ge- 
neva and of Turin, above the fea at Genoa, were ob- 
tained. In the table it will be obferved, that there is a 
column for the reduced temperature of the air, on ac- 
count of the expolition of the thermometer to the Sun’s 
(!) Having recomputed the whole of Mr. de luc’s obfervations on Saleve, 
and claffed them according to the months in which they were made, I intended, 
at one time, to have given a general table, comprehending the mean refults of 
all of them : however, this is now become unneceffary, fince a very refpe£lable 
and ingenious member of this Society hath had opportunities of making many 
curious and interefting obfervations on thofe very heights, which cannot fail of 
being perfectly fatisfa£lory ; and who, * at my requeft, was fo obliging as to 
determine the height of the Dole geometrically. On this mountain Mr. de luc 
had made barometrical obfervations, whofe refults differing confiderably from 
the altitude, 4182 feet above the lake of Geneva, as taken by Mr. fatio de 
duillier, made me fufpeft there was an error. In fa£t it appears, from the 
laft meafurement, that the fummit of the Dole is 4293 feet above the furface of 
the lake, which gives for the vertical diftance of Mr. de luc’s barometer 
4210 feet, 
rays:: 
