Thunder-storms. 283 



powder ; others employed mortars, larger or smaller, and it was 

 usually from heights that these explosions were made ; and the 

 consumption of mining powder, for this purpose alone, was 

 from nine to twelve hundred-weight a-year. 



This process of the Marquis of Chevriers was not confined to 

 the Mdconnais. Not long ago a mayor in the neighbourhood of 

 Blois, informed me, that in his commune, they likewise employ- 

 ed these mortars on the approach of thunder-storms, and he 

 requested to know if science had conferred its approval upon 

 the custom ; a query which, by the way, I may remark, seems 

 to shew that usage had not completely demonstrated its utility. 



The Bavarian or Maconnaise mode of dissipating thunder- 

 storms has been hitherto based upon an opinion of mariners, 

 and upon the solitary observations made in the seas off the 

 Spanish main ; but in meteorology the experience of a few days 

 is a very slender foundation for a general conclusion. In taxing 

 my memory to try if I could not discover some fact which 

 might support that one recorded by Forbin, I found one which 

 was entirely opposed to it, and, which is somewhat remarkable, 

 it also is derived from an admiral of the time of Louis XIV., 

 and founded upon observations made upon the eastern shores of 

 South America. 



Come back then, in thought, to the month of September of 

 the year 1711, and you may picture the squadron of Duguay- 

 Trouin before Rio Janeiro. This fleet, composed of the fol- 

 lowing ships, Le Lys^ Le Mag-nanime, Le Brillant, UAchille^ 

 Le Glorieux, and Le Mars; also V Argonaute^ UAmazone^ La 

 Bellone and UAigle frigates, and many other vessels of smaller 

 dimensions, was employed the whole day of the 12th to force 

 the entrance into the roads, defended by the formidable artillery 

 of a great number of forts, and also by that of four ships and 

 three frigates. The interval from the 12th to the 29th was oc- 

 cupied day and night in an unceasing contest of musketry and 

 artillery. The galliots threw bombs, the Portuguese set fire 

 to many mines, blew up many of their ships, burned many, 

 of their magazines, &c. &c. Finally, on the 20th, the day on 

 which the place was taken, two of Duguay-Trouin's vessels, Le 

 Brillant and Le Mars, the battery of the island of Chevres, 

 consisting of five mortars and eighteen twenty-four pounders, 



