S, &C. 5 



material creation, and by causing all bodies to tend 

 to one common centre, retains every thing in its 

 place, and thereby gives consistency and adhesion to 

 all the different parts of the immense structure. 

 Your enquiring mind will at a maturer age explore 

 all those wonders of nature : at present I will ende- 

 vour to direct your attention to things more within 

 t4ie limits of your capacity. I will briefly h> 

 inforin you that the earth is surrounded with an at- 

 mosphere of air, more condensed near the earth nml 

 at a greater elevation more rarefied. The height to 

 which this atmosphere extends i^ generally supposed 

 ft> be about sixty miles, above which elevation there 

 -are neither clouds nor wind, and the lightness of th 

 air would prevent any animal from breathing. The 

 winds which continually range over the earth are no- 

 ihingmore than air put in motion, chiefly by thft 

 means of heat. When any part of the air is heated 

 by the rays of the sun or any other cause it is ex- 

 panded and becomes lighter; and as the lightness 

 causes it to ascend, it leaves a partial vacuum info 

 which the surrounding air, which, like water and 

 every other fluid, never rests until it has found ils 

 level, rushes in, iirorder to till up the void and restore 

 the equilibrium. This simple process, of which thft 

 Qtf'ects are exceedingly extensive, meeting with vari- 

 ous checks and interruptions from an infinity of ob- 

 stacles, is the sole cause of all th<- agitations whirh 

 we perceive in the air, and which sometimes burst 

 forth into the most furious tempest*, or the most de- 

 structive hurricanes : all thi.< is produced by the 

 precipitancy of the condensed air rushing towards 

 Koine part where a partial vacuum is caused by ex- 

 treme rarefiaction. 



Clouds are nothing more than a collection of misty 

 vapours exhaled by th^ sun from the sea and most 

 parts of the earth, and suspended in the air i-n such 

 a state of condensation, that by intercepting the rays 

 of the sun they form a shadow and appear dark. The 

 clouds seldom ascend to the height of more than a 

 mile ; and on the tops of high wouiUaijid it i* co> 

 c 



