75 © Col. roy’s 'Experiments for 
the aggregate refult of Mr. de luc’s obfervations, where 
the lowermoft barometer flood about 1300 feet above 
the fea, the equation for the fame temperature feemed 
n6t to exceed Laftly, thefe circumftances being 
confronted with the refults of Mr. bouguer’s obferva- 
tions, where the lowermoft barometer flood from 6000 
to 8000 feet above the fea, the mean equation for 55’ 
was only &L, which gives for the heat of 5 2 0 . Now 
thefe Peruvian obfervations, which I believe to be ex- 
ceedingly good from the fteadinefs of the barometer in 
that part of the world, being fubllituted in lieu of thofe 
not yet obtained in our own quarter of the globe, there 
feemed to me to be a neceflity for concluding, that the 
equation for middle latitudes, with any afligned tempe- 
rature above or below the zero of the fcale, diminifhed 
as the height of the place above the fea increafed ; which 
confequently implied, that the magnitude of the loga- 
rithmic terms increafed fafter than the dilatations of the 
air. But when tire comparifon was carried yet farther, and 
the obfervations in Peru and at Spitzbergen were fairly 
brought into one view, there appeared to be fufficient 
grounds for fufpecting, if not abfolutely for concluding, 
that there could be no fixed zero for the fcale depending 
on the temperature of the air; but that it would change 
with the denfity of the atmofphere appertaining to the 
latitudes. 
