150 EXPERIMENT'S and OBSERVATIONS 



THESE, and fuch like, were the furmifes which offered them- 

 felves previous to my entering upon the fubje<5l for the fecond 

 time, and which I was defirous to bring to the teft of experi- 

 ment, not without fome hopes of being able to account for the 

 phenomenon in queftion, by principles already known and fa- 

 miliar to tis. This attempt, however, ended very unfuccefs- 

 fully, as may be feen by the account given in my paper for the 

 year 1781. Indeed, neither the weather, nor other hinder- 

 ances, then admitted of purfuing the experiments far ; though 

 ftill enough was accompliihed to mow fomething anomalous 

 and obfcure in regard to the caufe fought after. 



IN this ftate, the fubjed lay by till the commencement of 

 the late rigorous feafon, when, having occafion to be frequent- 

 ly at the Obfervatory at late hours, on account of the approach 

 of the Georgium Sidus to its oppofition, I was again led to re- 

 fume the experiments upon cold. 



IN order to proceed with more certainty and expedition, I 

 had now ready a fet of ticklifh thermometers, with naked balls 

 and flender ivory fcales, and all very nearly agreeing, as to their 

 dimenfions and diflance betwixt the fixed points. Thefe ther- 

 mometers, upon which I fet a high value, were the laft my fa- 

 ther ever conflrudled ; and for which he felec~led very xac~t ca- 

 pillary tubes, having their bores, according to his improved 

 method, fo much of a flattened oval form, as to prefent a very 

 obvious broad pillar of quickfilver upon the fcale, notwith- 

 ftanding the fmallnefs of the balls ; a property highly conve- 

 nient, efpecially when nice experiments are to be carried on by 

 candle-light, and in the open frofty air. 



MY father's (late of health not permitting him to encounter 

 the inclemency of the weather in fuch night-obfervations, my 

 firft objecl was, a repetition of feveral of the experiments for- 

 merly made, before proceeding to others, which, by this time, 

 had been planned with a view of carrying forward the enquiry. 



DECEMBER 



