Meteorology. — 493 
hemisphere to invade that of the southern, 
during our summer, and vice versa, in winter ; 
yet I conceive it never can be so effectual as 
to restore a perfect equilibrium during the 
season, but will leave an excess of aqueous 
vapour in our hemisphere, unbalanced either 
by air or vapour, of the opposite hemis- 
phere, 
2, Of the Thermometer, 
My thermometer is situated out of a win- 
dow on the second floor, about 16 feet above 
the ground, and about 6 inches from the 
wall; it has an eastern aspect, and open, airy 
situation, is not affected by the sun, except 
in a summer’s morning, and it is then duly 
shaded to prevent the sun’s influence. The 
observations are taken three times a day, as 
with the barometer, at 8 in the morning, and 
at 1 and 11 in the afternoon. I have some 
reason to think the observations give a mean 
temperature, rather below than above the 
true mean, The temperature of springs in 
this place is usually between 48° and 50° ; 
probably the mean annual temperature may 
be nearly 49°. The general annual mean as 
determined by my thermometer, is between 
47° and 48°,—The monthly means for July 
