during the Intense Frost of 1776-7. ^ 



that critical moment, the tube of the thermometer 

 broke, which put an end to the experiment, and left 

 the degree of cold undefined, which probably, how- 

 ever, must have been very little, if at all, short of 40° 

 below zero. Had the entire congelation been com- 

 pleted, it would have proved the possibility of what, 

 at that period, was judged to be utterly impractica- 

 ble, especially in the mild climate of England, viz. 

 the freezing of mercury, and converting that fluid 

 semi-metal into a perfect and malleable metal. 



This curious discovery, which had been lately ef- 

 fected by Professor Brown, at St. Petersburgh, and 

 which had surprized all Europe, seems here to have 

 been on the point of being realized in Great-Britain, 

 though, from the supposed impossibility, I was led 

 to discredit my own senses. But since the freezing 

 point of mercury has been ascertained to be 39°, or 

 not to exceed 40° below zero, the congelation has 

 been repeatedly accomplished in England, under very 

 inferior degrees of natural cold, aided by frigorific 

 ynixtures. 



January 31st to February 1st. The barometer 29^, 

 the thermometer 16°; the atmosphere serene, and 

 much more mild, 



February 2d. Wind south ; barometer at 29 ; a 

 warm, misty moriting, succeeded by a pleasant, spring- 

 like day, which ushered in a very gentle and agree- 

 ble thaw, the thermometer, within the last 48 hours, 

 having risen rapidly from below zero to 40°: such 



