367 



connexion and proved its dependence are, temperature ^ and 

 the total quantity of moisture present in the air, as shown by 

 the dew point. Indeed these two phenomena, as the author 

 remarked, are referribie to each other, the temperature pro- 

 ducing evaporation, and the force of electricity at any 

 period being shown to be almost exactly proportional to 

 the tension of the vapour so produced. 



The hour of the first electric minimum was shown to 

 be about 3 a. m., the electricity increasing with the tem- 

 perature until 10 A.M., when a slight decrease occurred; 

 the electric tension again commences rising at about 11 a. m.; 

 and continues to increase until about 2^ 45"\ p. m. — all 

 these movements being in exact proportion to the elevation 

 of the dew^ point and temperature. At 3 p. m. the dew point 

 and temperature begin gradually to lower, as does also the 

 electricity (but not so quickly); but from 5 to 7 p. m., the 

 electric intensity rises, being acted upon and increased by 

 the precipitation of the evening dew, which has set free the 

 latent electricity of the condensed vapour, in conformity 

 with the experiment of Volta. Again, from 7 p. M., the 

 electric intensity weakens rapidly, and descends in common 

 with the dew point and temperature, until they all reach their 

 minimum about 3 a.m. 



Thus the patient investigation of this subject has laid 

 bare the cause of the varying diurnal intensity of the elec- 

 tric fluid, — showing it to be the result of evaporation, which, 

 besides its agency in carrying the electric fluid from our 

 earth to the upper regions of the air, daily returns it to us 

 by the conducting power of this vapour, in the direct pro- 

 portion of its quantity. 



Dr. Smith read a paper **on the Irish Coins of Ed- 

 ward the Fourth," the chief object of which was to endea- 

 vour to fix the dates of the numerous coinages of this reign 

 with more precision than had been attained before. 



