220 AIR AND WATER. 



which opens downward into the well or pit that 

 supplies the water; and, whatever the heating cause 

 is, whether warm air or warm earth, it converts the 

 water in that boiler into steam. The steam is con- 

 fined by the pressure of the column of water in the 

 pit or well, which is open to the air. But when the 

 steam reaches a certain heat, the pressure of the 

 column can no longer resist it, and it forces the 

 water up in a high and powerful jet. The steam, and 

 most likely also heated air, escape along with the 

 water, and the water is cooled, so that it sinks down 

 in the pit, and again enters the boiler, so as to shut 

 the opening till the steam be sufficiently powerful 

 to drive up the column of water. 



SECTION VIII. 



Observation of the Water and the Earth. 



NOTWITHSTANDING the length to which the preced- 

 ing section has extended, it contains only a few hints 

 on an exceedingly limited number of those conclu- 

 sions relating to the agency of air and water in the 

 economy of nature, to which even the most common 

 observer must arrive, if he reflects as well as ob- 

 serves. There is scarcely any thing natural that 

 happens in which one or both of these substances 

 are not concerned, either as materials, or as media 

 by means of which other substances are enabled to 

 act upon each other. Thus, whatever we observe 

 be it in the solid earth, down to the bottom of the 

 deepest mine be it in the ocean, "deeper than 

 plummet ever sounded" be it in the atmosphere, as 

 high as a foot can climb or a wing cleave, a vapour 

 ascend or a meteor be formed be it at any time, 

 or at any place be it in plants, from the little 

 moulds of which the spora or seeds probably circu- 





