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Art. XXIII. Account of the remarlcabU Depression of the 
Thermometer^ and Rise of the Barometer ^ in January 1820, 
TDhE meteorological facts which presented themselves in the 
month of January 1820, are so singular in themselves, and have 
been so unprecedented in this climate, that we have thought it 
advisable to record some of the best authenticated observa- 
tions. 
1. Obsermtions made at Perth. — On the night between Mon- 
day 17th and Tuesday 18th January, (the coldest night perhaps 
ever remembered in this country), the thermometer stood at Perth, 
in a northern exposure, so low as — 10° on Fahrenheit’s scale, 
being not less than 42° below the freezing point. During the whole 
of Tuesday, the instrument remained under zero, except for a 
short interval about noon, when it rose to T. The effects of 
this great reduction of temperature were such as usually accom- 
pany the most intense cold. The evaporation from the surface 
of the ice on the Tay, being condensed in the air almost imme- 
diately after its formation, produced over the river a partial fog, 
which, being gently wafted to the neighbouring trees, attached 
itself by degrees to the branches, and gave birth to innumerable 
and diversified exfoliations of the most singular beauty. The 
bridge being elevated above the vapour, a remarkable appear- 
ance was observed, during sunshine, by a spectator who raised 
his head a little above the parapet, so as to throw his shadow on 
the fog below : a gigantic figure was seen projected on the 
moving vapour, (such as has been frequently noticed under si- 
milar circumstances, in Alpine countries,) surrounded by a 
beautiful halo^ and throwing off, in every direction, radiations 
which exhibited distinctly all the prismatic colours. The effect 
was most striking when the sun was a few degrees above the 
horizon, and was barely perceptible after mid-day. So great 
was the intensity of the cold, that the windows of apartments 
where a constant fire was kept, were covered with a thick coat- 
ing of ice, which obscured the light of day ; and liquors of va- 
rious kinds were completely frozen, in situations where it might 
have been supposed they were beyond the reach of frost. The 
sudden increase of temperature which took place from Tuesday 
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