STUDY IV. 251 



fmall grains of copper. It is impoflible to doubt 

 that it muft be impregnated with that metal -, ^nd 

 to the copper we muft, perhaps, afcribe the virtue 

 which it pofleffes of attrading the clouds. For 

 it is known by experience, that this metal, as well 

 as iron, has the property of attrading thunder. I 

 do not know of what materials other peaks are 

 compofed ; but it is very remarkable, that at the 

 fummit of the Andes, and on their ridges, are 

 found the gold and filver mines of Chili and Peru, 

 and that in general, all mines of iron and copper 

 are found at the fource of rivers, and in elevated 

 (ituations, where they difcover themfelves by the 

 fogs which furround them. Whatever may be in 

 this, whether this attraâiive quality be common to 

 granite, and to rocks of a different nature, or whe- 

 ther it depends on fome metal which is amalga- 

 mated with them, I confider all the peaks in the 

 world as real eledric needles. 



But it was not fufficient that clouds fhould col- 

 left and fix on the tops of mountains, the rivers 

 which have their fources there, could have only an 

 intermittent courfe. As foon as the rainy feafon 

 was at an end, the rivers muft have ceafed to flow. 

 Nature, in order to remedy this inconveniency, 

 has contrived, in the vicinity of their peaks, lakes, 

 which are real refervoirs, or cifterns, of water, to 

 furnifli a regular and conftant fupply to their ex- 

 penditure. 



