16 Eloge of Alexander VoUa, 



ance as the foundation of a very curious branch of meteorology. 

 For this purpose a few words will suffice. 



When the insulated metallic vase in which the water evapo- 

 rates, becomes electrical*, it is because this water, in order to 

 pass from the liquid to the aeriform state, derives from the bo- 

 dies which it touches, not only heat but likewise electricity. The 

 electrical fluid is therefore an integral part of the great masses 

 of vapour which are daily formed at the expense of the water 

 of the sea, lakes, and rivers. These vapours, rising into the 

 higher regions of the atmosphere, there meet with a cold which 

 condenses them. Their electrical fluid is disengaged, accumu- 

 lates, and the weak conductibility of the air prevents it returning 

 to the earth, whence it originated, unless accompanied with rain, 

 snow,' and hail, or in violent discharges. 



Thus, according to this theory, the electrical fluid, which, in 

 a stormy day, darts its dazzling flash through every quarter of 

 the sky, — which produces such resounding explosions, and, when 

 falling on the earth, carries along with it conflagration and 

 death, — is the product of the daily evaporation of water, the 

 inevitable consequence of a phenomenon developed in such im- 

 perceptible shades that our senses cannot mark its progress ! 

 When effects are compared with causes, what singular contrasts 

 must Nature be confessed to present to our contemplation ! 



I now arrive at one of those rare epochs, in which a remark- 

 able and unexpected fact, usually the result of some fortunate 

 accident, is matured by genius, and becomes the cause of a re- 

 volution in science. The detailed picture of important results 

 brought about by trifling causes, would not perhaps be less in- 

 teresting in the history of the sciences than in that of nations. 

 If any one undertake the delineation, that branch of physics 

 known under the name of Galvanism, will occupy one of the 

 most conspicuous places. It may, in fact, be proved, that the 

 immortal discovery of the pile is connected, in the most direct 

 manner, with a slight cold caught by a Bolognese lady, in 1790, 

 and a dish of frog-soup prescribed by the doctor as a cure. 



• It is now known that the experiment does not succeed when distilled 

 water is employed. This circumstance, certainly a very curious one in rela- 

 tion to the theory of evaporation, detracts nothing from the importance, in a 

 meteorological point of view, of the labours of Lavoisier, Volta, and Laplace, 

 since the waters of the sea, lakes, and rivers, are never perfectly pure. 



