152 EXPERIMENTS and OBSERVATIONS 



when feen through the fame opening, promifed a very good ob- 

 fervation. 



UPON going abroad, I found the face of things entirely 

 changed, the heavens being now overcaft, not however by 

 clouds, but by a thick uniform haze or fogginefs above, which 

 obfcured even the ftars of the firft magnitude. Being now 

 out of doors, I thought of vifiting the thermometers j and, 

 upon approaching them with fome caution, I found, not with- 

 out -furprife, that the excefs of cold, at the furface of the fnow, 

 had almoft quite vanifhed. The thermometer in air pointed to 

 -K6, two degrees higher than before, and the one upon the 

 fnow to + 4 : This was at fifty minutes paft eleven. Till half 

 paft twelve the fogginefs above continued rather to increafe, 

 when both thermometers pointed exactly to the fame degree 

 + 7 j which, at fo low a temperature, and from the fuddennefs 

 of the change, I could not help regarding as very remarkable, 

 efpecially as nothing fimilar to this had occurred in my former 

 obfervations. 



By half an hour after one in the morning, the ftars be- 

 gan again to mine out j when now I was amufed to find the 

 excefs of cold at the furface of the fnow returning. The air, 

 by this time, was + 8, and the fnow + 4. As the morning ad- 

 vanced, the atmofphere turned more and more ferene, and the 

 thermometers came to differ no lefs than eight degrees. The 

 obfervations made at this time are fet down in the following 

 regifter : 



DECEMBER 



