OBSEEVATIONS OF ATJIOSrUEniC ELECTRICITY. 



44< 



and it is found that, as a rule, the curves of the three series closely resemble 

 one another, indicating in all cases a much greater variation in tension 

 during the twenty-four hours in the winter months than in the summer, 

 the relative values of the diurnal range being for 1880, in volts — 



the mean for the year being C6. 



Table IV. — -Values of Electrical Tension corresponding to Wind- 

 Velocities. 



The variation of Atmospheric Electricity at Kew with some of the 

 other meteorological elements has already been briefly investigated ; 

 Professor Everett having indicated the similarity between the curve of 

 diurnal variation of tension with that of the diurnal variation of the 

 bayometer, whilst Mr. Birt directed his attention to the relation between 

 electricity and the quantity of aqueous vapour in the air. 



The striking resemblance between the curves of diurnal variation of 

 electrical tension and of barometric pressure has also been found to run 

 all through 1880, and the same fact has been noticed at Greenwich by 

 Mr. Ellis, as well as the apparent lagging behind of the barometric curve 

 by from one to two hours. 



