918 Transactions of tbe American Institute. 



operation, adequate to such disturbance of the electric equilibrium 

 between the earth and its surrounding atmosphere. Do not the 

 potent rays of the sun, in their vaporizing effect, constitute auch a 

 force ? 



Pouillett and others have shown that no electricity is produced by 

 tlie evaporation of distilled water, but if an alkali or a salt is dis- 

 solved, even in small quantity, there is chemical disaggregation and 

 ■^'apor is positively, while the solution is negatively electrified. Tlie 

 reverse is tlie case, if the water contains acid. Volta was the first 

 to show that the evaporation of water produced electricity. Now, 

 as the w.aters of the whole ocean hold salts in solution, Pouillett is 

 disposed to see in this evaporation the source of atmospheric electri- 

 city. Desossure concurs with Volta and Pouillett in this theory. 



I take it, therefore, as established that the vapor of the atmosphere 

 as a whole, is charged with positive while the earth and ocean are 

 charged with negative electricity ; although the solid earth and the sea 

 are, in some degree, in opposite electrical states ; the sea being posi- 

 tive and the earth negative. It is also a fact, now well established, 

 that the higher we ascend the more highly' positive is the tension. 



Bequerel and Peltier have demonstrated this most clearly ; Quet- 

 elet, experimenting with a balloon and electrometer, satisfied himself, 

 by a great number of observations, that the electric intcnsit}'^ of the 

 air, increases proportionately to the height. I venture therefore to 

 suggest the probability, that if an insulated conducting wire were 

 to be erected, having a ground connection in a valley, and being con- 

 nected wUli a large surface of wire gauze, above the top of a neigh- 

 boring mountain, so as to form a good atmospheric connection, a 

 current would be, at most times, propagated through the wire sufli- 

 ciently intense to operate a Morse telegraph, and that the higher the 

 mountain the more intense would be the current. The intensity will 

 be variable, however, according to the hygrometic condition of the 

 atmosphere. 



A positive cloud, too, coming near the upper portion of our tele- 

 graph line, may change its electric condition by induction, so as to 

 neutralize the current, or even to cause it to flow in the opposite 

 direction. 



Evaporation, 



According to the learned Dr. Buist, as quoted by Lieut. M. F. 

 Maury, in his physicalgeography of thesea,pagell,the average evap- 

 oration from the ocean equals about nine feet of water per annum ; 



