448 



calculated by my formula, in its complete and less perfect 

 form, from the observed temperatures of a wet and dry 

 thermometer. 



(Top of Sugar-loaf, April S3, 1840.) 



^ = 60°-8; f-5S°'2; t-t'zzlo.Q. ^-28-516. 



f' (by Daniell's hygrometer) zz 47.5. 



i'^ (by formula /'=/ - '0114 {t - f) X ^^) = 46°-8. 



f' (by formula/^ -/ - -0114 (^ - f) ) = 46^-22. 



P — f 

 " Thus, by neglecting the factor ^-^~, which, in the pre- 



ceding observation, zz '9366, the calculated dew-point comes 



out 0°'58 too low. This, however, may, under ordinary 



circumstances, be considered as an extreme error; for t — t' 



p — f 

 is seldom so high as 7-6, and scarcely ever so low as 



•9366, at least in this climate." 



May 25. 

 REV. H. LLOYD, A. M., Vice-President, in the Chair. 



A paper was read by the Secretary, being a continuation 

 of Mr. George J. Knox's researches " on the Direction and 

 Mode of Propagation of the Electric Force, and on the 

 Source of Electrical Development." 



In the commencement of this paper the Author describes 

 some experiments, from which he concludes that all fluids 

 convey the electric force through their substance ; while 

 with regard to solids no regular law exists, some conveying 

 the electric force through their substance, while others con- 

 vey it along their surface. He next considers the source of 

 electrical development, and shows that it must originate in 



