[ '5° ] 



of Farenheit's fcale, which is three degrees above the general 

 temperature of the northern coaft, and equal to that of Cork, 

 though fituated above three degrees of latitude farther to the 

 fouth : while the water, iffuing from a new level opened in 

 the year 1787, produces a mean temperature only equal to 46°, 

 which is two degrees below that of the northern coaft itfelfj 

 fo that in thefe pits there is a variation of five degrees of 

 temperature at the leaft *. 



For this reafon experiments are rather to be derived from 

 covered wells of pure water ; and it matters little whether fuch 

 wells be fupplied by fprings, or by a flow filtration, fince the 

 water, long refting at the bottom of each well, will always give 

 the temperature of the earth at that depth ; and confiftence, or 

 inconfiftence, in experiments made at different places not very 

 diftant from each other, will always enable an attentive obferver 

 to conjedure concerning the fairnefs of the trial. 



The firft table, which is annexed to this paper, marks the 

 temperature of the coaft of Ireland in different degrees of latitude. 

 By this it will appear that there is, at prefent, a difference 

 of 3— degrees of heat, (as marked by Farenheit's fcale) between 

 our northern and fouthern coaft, through a difference of latitude 

 equal to 30 18'; fo that the variation of heat, in our ifland, is 



* This latter level is opened on a little bay called Port na Graigh, (the Mares 

 Port) ; and I was condufted to it in confequence of the complaints of the workmen, 

 wlio fufFered very much from the intenfity of the cold. It was then the month of 

 Augufl, 1787, and yet the temperature of the pit was fo low as 47, 5. 



at 



