Heorary Oscillations of the Barometer. 195 
It appears from this table that the rise in the mercurial column 
from 8 A.M. to 4 P.M. was nearly constant, and upon further 
examination it will be found that in the only two exceptions of any 
amount, namely the months of January and March 1823, some 
unusual influence prevailed in the atmosphere. The first was 
distinguished by an unusually high mean temperature, and fre~ 
quent storms of wind. Captain Parry remarks in his Journal, 
“from the morning of the 24th till midnight on the 26th, the 
mercury in the barometer was never below 30.32 inches, and at 
noon on the latter day had reached 30.52 inches, which was the 
highest we had yet observed it in the course of this voyage. 
This unusual indication of the barometer was followed by hard 
gales on the 27th and 28th, first from the S.W., and afterwards 
from the N.W., the mercury falling from 30.51 inches at 8 P.M. 
on the 26th, to 30.25, about 5 P.M. onthe 27th, or about 0.26 of 
an inch in nine hours before the breeze came on. At midnight on 
the 27th it had reached 29.30, and on the following night 29.05, 
which was its minimum indication during the gale. These high 
winds were accompanied by a rise in the thermometer very unusual 
at this season of the year, the temperature continuing above 0° 
for several hours, and very near this point of the scale for the 
whole two days.” 
The month of March, on the contrary, was as much below the 
mean in temperature, as January was above it, and the observation 
renders it probable that the usual course of the season was modi- 
fied by some extraneous cause. ; 
Iam aware that it may be objected, that these observations 
were not made with all the precision that the accurate determi- 
nation of such small quantities requires, and particularly that the 
heights of the barometer were not corrected for the variations of 
temperature. The objection, to some extent, is certainly valid, and 
it is much to be lamented that the advantages of the utmost at- 
tainable degree of precision in these observations have not hitherto 
been duly appreciated : but when it is recollected that the instru- 
ment made use of was placed in the cabin of the ship, where con- 
siderable pains were taken to maintain an equal temperature, it 
