f 327 ] 
night, with fome water in it, I was furprlzed to 
find the furface of the water frozen over, the like 
not having happened before in that place. Upon 
this, I defined my fen to try the cold by a thermome- 
'ter, as I imagined it behooved to be very intenfe. 
The experiment was foon after made, by exppfing 
a thermometer at a high North window, and free 
from the walls of the houfe ; in which fituation it 
had not remained for a quarter of an hour, when we 
found the mercury had fallen fo low as to 5 deg. of 
Fahrenheit’s fcale. 
Although I had expeded a great degree of cold, 
yet 1 was not quite prepared for fo extraordinary a re- 
port as that which the thermometer now gave me. 
My doubts were, however, foon fettled, by examin- 
ing matters with more attention, and by finding the 
firif thermometer verified by my ftandard one, 
which was now hung out befide it. 
Being thus fatisfied that there was no fallacy in this 
preliminary obfervation, it naturally occurred, that the 
cold, however intenfe it now was, might have been 
much more fo at fome earlier hour of the morning. 
But how to afeertain this, and to recover the lofi: ob- 
fervation, was the difficulty. In the eagernefs of 
our difappointed curiofity, we were difpofed to mag- 
nify this golden opportunity, which had now efcaped 
us, and to refled upon it with regret, when luckily 
a little invention helped us out. A notion fuggefied 
itfelf, that, if we went very warily to work, we 
might perhaps furprize thole imagined colds ftill 
lurking under the furface of the fnow, which at that 
time lay thick upon the ground. 
I need 
