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Meteorology. 485 
been boiled in order to expel the air and mois- 
ture more effectually. This was found to 
stand nearly 2, of an inch higher than the 
previous one, and a few hundredths higher 
than it stood at originally ; owing in part at 
least to the elevation or height of the baro- 
meter,. above the level of the sea being 10 
or 12 feet more in the first period than in the 
latter. In order to allow for the rise and fall 
of the mercury in the bulb, the scale of 4 
inches was made only -3.98 inches, .and sub- 
divided into tenths as usual. The observa- 
tions throughout the whole series were taken 
3 times each day, namely, at 8 A.M. and at 
land 11 P.M.—The new or last mentioned 
barometer has been used for the last 15 years, 
commencing with January 1804; and. it 
may be right to observe, that for the 3‘last 
months of 1798 it was used, but the reduc- 
tion was applied to the monthly means, in 
order to make the observations of the whole 
year uniform. . As the adhesion of the mer- 
cury. to the tube is more or less observable in 
great variations, I make it a practice to give 
one or.two gentle vibrations to the mercury 
prior to any observation, which I think .is 
more accurate than using a wider tube rang 
out such vibrations. 
_ The elevation of my wilt ates shove the 
