10 Eloge of Alexafider Volta. 



Pliny the naturalist relates, that Tiillus Hostilius was struck 

 with lightning, for having carelessly performed the ceremonies 

 by means of which Numa, his predecessor, had caused the thun- 

 der to descend from heaven. On the other hand, some imagined 

 that they had found in the same occurrence something not pre- 

 viously known, viz. that in certain circumstances a bar of njetal, 

 somewhat elevated, attracts from the clouds not only impercep- 

 tible sparks, but what may be called streams of electricity. The 

 discussions subsequent to this period on the efficacy of conducting 

 rods, are destitute of interest. I do not except from this cha- 

 racter the warm debates which for some time divided the learned 

 in England, on the conductors terminating in a point or in a 

 ball. No one is now ignorant that George III. was the pro- 

 moter of this dispute ; that he declared for conductors termi- 

 nating in a ball ; while Franklin, his antagonist in political 

 questions of immense importance, wished them to end in a 

 .point. This discussion, therefore, properly considered, is rather 

 a trifling incident in the history of the American revolution, than 

 one connected with science. 



The results of the experiment at Marly were scarcely known, 

 when Lemonnier, of this Academy, erected in his garden at St 

 Germain-en-Laye, a long bar of metal, in a vertical position, 

 which he insulated with greater precaution than before ; and from 

 that moment the electrical spark appeared not only when the 

 thunder was heard, and the atmosphere full of threatening clouds, 

 but even when the sky was perfectly serene. A beautiful dis- 

 covery thus resulted from a modification, apparently of the most 

 insignificant kind, of the apparatus first used by Dalibard. 



Lemonnier ascertained that this lightning in a clear sky, the 

 existence of which he had just discovered, was liable during the 

 whole twenty-four hours to regular variations in its intensity. 

 Beccaria made some excellent observations on the laws of this 

 diurnal period, and established the important fact, that in all 

 seasons, at all heights, and during the prevalence of every wind, 

 the electricity of a clear sky is constantly positive or vitreous. 



Following in regular order the progress of our knowledge in 

 atmospheric electricity, I now arrive at the works with which 

 Volta has enriched this important branch of meteorology. His 

 labours have been directed to the improvement of the means of 



