I 



231 



of the progression of elastic force, and — 121° the zero of same 

 temperature. (3.) That Dr Dalton's theory of temperature does, 

 with very slight modifications, represent accurately our knowledge 

 of the law which connects the temperature wilh the elastic force of 

 vapour. (4.) Expressions may be derived from this theory of the 

 same form as the empirical formulae at present in use ; and these 

 are : 



For Dr Dalton's experiments below SIS'", the temperature being 

 reckoned from — 175°, or t = temp. F. + 175°. 



(14.) Log ( = 0.12965 logF + 2.587711 



(15.) Log F,= 7.71307 (log « — 2.587711) 



For the mean of the experiments of the French Academy and 

 the Franklin Institute above 212^ the temperature being reckoned 

 from — 12r or t = temp. F. + 121°. 



(16.) Log t =0.1557634 log F + 2.5224442 



(17.) Log F,= 6.42 (log t — 2.5224442) 



For the following substances, we obtain, by means of a single 

 modulus or constant number, derived from Dr Dalton's experi- 

 ments for each substance, which is substituted for 2.602, the mo- 

 dulus for vapour of water in equation (12). This modulus is 2.57 

 for acetic acid, 2.700 for alcohol, 1.978 for sulphuret of carbon, 

 and 2.00 for ether ; and the formulae are as follows : — 



^ , ^ , ( Log t = 0.12483 log F + 2.5428254 



Alcohol l^ „ 



( Log Ft = 8.01090 (log t — 2.5428254) 



, J Log t = 0.178873 log F + 2.4345689 

 ( Log F = 5.59003 (log ( — 2.4345689) 



Acetic Acid I Log t =0.13116 log F + 2.5965971 



{ Log F = 7.52427 (log 1—2.5905971) 



oiu . fn u S Log t = 0.18277 log F + 2.4548449 

 Sulphwret of Carbon 1..° -.-,.,. 



*^ ( Log F = 5.4714 (log t — 2.4548449) 



2. Abstract of a Paper on Results of Observations made with 

 Wheweirs New Anemometer. By Mr John Ranken. 

 Communicated by Professor Forbes. 



In laying the results of these observations before the Society, it 

 was thought necessary to make a few remarks in explanation of 

 the manner in which they were made. 



