LETTER VH. 



mon to see them floating below. The wonderful va- 

 riety of colours which they exhibit is entirelv owing 

 to their situation in respect of the sun, and the diffe- 

 rent reflections of his light, and their various figures 

 result from their loose and voluble texture which 

 disposes them to resolve into any form according to 

 the force and direction of the wind. 



Rain proceeds from the condensation of the clouds 

 by the effect of the cold. When they are greatly 

 condensed they become too heavy to float in the air 

 and then descend in drops. 



In winter, when the regions of the air are intensely 

 cold, the clouds quickly pass from that state of con- 

 densation which might reduce them to rain, into 

 that which converts them into ice, so that as soon as 

 they begin to form very small drops of water, the. 

 particles freeze, and many of them touching one 

 anotner compose flakes of snow. 



When the drops, already beginning to descend, 

 meet with a very cold air which freezes them, they 

 form hail : the difference between that and snow 

 proceeding from the circumstance of the clouds being 

 more or less condensed at the moment in which the 

 congelation took place. 



Thunder and lightning are produced by the elec- 

 trical fire contained in a cloud, which bursts forth in 

 flashes and causes a tremendous noise by its explosion. 

 The thunder however is no more than a mere sound 

 productive of no bad effect, the lightning is the de- 

 structive agent. It flies with incredible velocity 

 from the clouds to the earth through every thing 

 that falls in its way ; and is attracted by high trees, 

 lofty and spiry edifices, and every kind of elevated 

 and pointed object, as also by most metals, especi- 

 ally iron. The precaution proper to be taken in a 

 thunder storm is to avoid taking shelter under a high 

 tree, or any lofty building, (an oversight which im- 

 proved fatal to numbers), and to chnse a situation at 

 the distance of about thirty or forty feet from such 

 elevated object", that by its attraction will almost in- 

 fallibly draw the lightning from the person so placed 

 and ensure his safety. Thrs" is an observation which 



