NATURAL HISTORY 
LETTER LXIL 
TO THE SAME. 
As the froft in December 1784 was very extraordinarj^, you, I 
truft, will not be difpleafed to hear the particulars ; and efpecially 
when I promife to fay no more about the fe verities of winter after 
I have finilhed this letter. 
The firft week in December was very wet, with the barometer 
very low. On the ydi, with the barometer at 28 — five tenths, 
came on a vafl fnow, which continued all that day and the next, 
and moft part of the following night ; fo that by the morning of 
the 9th the works of men w.tc quite overwhelmed, the lanes 
filled fo as to be impalTable, and the ground covered twelve or 
fifteen inches without any drifting. In the evening of the 9th 
the air began to be fo very fharp that we thought it would be 
curious to attend to the motions of a thermometer : we therefore 
hung out two; one made by Martin and one by Dollond, which 
foon began to fliew us what we were to exped ; for, by ten 
o'clock, they fell to 21, and at eleven to 4, when we went to bed. 
On the loth, in the morning, the quickfilver of Dollond's glafs 
was down to I:alf a degree belozv zero ; and that of Martin's, which 
was abfurdly graduated only to four degrees above zero, funk quite 
into the brafs guard of the ball ; fo that when the weather became 
moft interefting this was ufelcfs. On the loth, at eleven at 
night, though the air was perfectly ftill, Dollomfs glafs went down 
to 
