Dr. 1U,AGDEN*S Hifory of 
his thermometer, and fiuck in the tube at - 46% that is, a 
few degrees below the true point of mercurial congelation. But 
the weather becoming milder two days afterwards, the frnalfc 
thread of quicktilver in the tube foon melted, and consequently 
lubbded. Pofiibiy it came much lower than Dr. g ME LIN hap- 
pened to obfetve it at noon ; for then the great body of quick- 
filver was undoubtedly in motion, afcending rapidly as it ex- 
panded by melting, till it came up to the degree that cor- 
refponded with the temperature of the air. Therefore, inflead 
of a change in that temperature from - 46° to — 108° in a few 
hours, and from - io8d up to — 19° in half an. hour,, which, 
would have been really aflonifhing, this observation only fhews 
that the cold, after having continued two days as much below 
- 39 0 as was fufficient to freeze mercury, at length abated. 20: 
or 30 degrees, perhaps very gradually no greater alteration, 
than frequently takes place in moft extra-tropical climates- 
A limilar inftance occurred at Kirenga Forts a few dtiys after- 
wards*, explicable in the fame manner. 
Again, on the 29th of December (O. S.);Dr. gmsxin found, 
his thermometer, which had been. Handing at - 40° early in. 
the morning, funk down to - ioo° at four in the afternoon*. 
He fubjpins the following remark -f . “ I obferved feme air 
“ in the thermometer, feparating the quickfilver for the fpace 
u of about fix degrees- Yeflerday evening I took notice of a 
44 fimilat appearance, except that the air was not then coHe&ed* 
44 into one place, but lay feattered in feverak I confidfered it 
“ as an accidental fault in the inferument, and attempted to> 
4< expel it by means of a Heel wire, but could not bear the 
‘• 4 cold- In the barometer, alfo, fome very fmall aii^bubbles 
* Reife. Theil. II. p. 625. 
t Ibid. p. 631*. 
5 
were 
