INTRODUCTION TO HYDROSTATICS. Ixi 



SECTION II. On Springs, Fountains, fyc. 



us iiow turn our attention to the various states in which the water 

 belonging to our globe exists. It is the same water which successively 

 forms seas, rivers, springs, clouds, rain, and sometimes hail, snow, and 

 ice. We will follow it through these various changes, and consider how 

 the clouds were originally formed. When the first rays of the sun warm 

 the surface of the earth, the heat, by separating the particles of water, 

 transforms them into vapour, which, being lighter than the air, ascends 

 into the atmosphere. The atmosphere diminishing in density as it is 

 more distant from the earth, the vapour which the sun causes to exhale, 

 not only from seas, rivers, and lakes, but likewise from the moisture on 

 the land, rises till it reaches a region of air of its own specific gravity, 

 and there it remains stationary. By the frequent accession of fresh 

 vapour it gradually accumulates, so as to form those large bodies 

 of vapour which we call clouds ; and these at length becoming too heavy 

 for the air to support, fall to the earth in the form of rain. If the 

 watery particles retained the state of vapour, they would descend only 

 till they reached a stratum of air of their own specific gravity ; but during 

 their fall several of the watery particles come within the sphere of each 

 other's attraction, and unite in the form of a drop of water. The vapour, 

 thus transformed into a shower, is heavier than any part of the atmos- 

 phere, and consequently descends to the earth. Observe, that if the waters 

 were never drawn out of the earth, vegetation would be destroyed by the 

 excess of moisture ; if, on the other hand, the plants were not nourished 

 and refreshed by occasional showers, the drought would be equally fatal 

 to them. Were the clouds constantly in a state of vapour, they could 

 never fall to the ground ; or were the power of attraction more than suffi- 

 cient to convert the vapour into drops, it would transform the cloud into 

 a mass of water, which, instead of nourishing, would destroy the produce 

 of the earth. We cannot consider any part of Nature attentively without 

 being struck with admiration at the wisdom it displays : we cannot con- 

 template these wonders without feeling our hearts glow with admiration 

 and gratitude towards their bounteous Author. 



Water, then, ascends in tne form of vapour, and descends in that 

 of rain, snow, or hail, all of which ultimately become water. Some of 

 this falls into the various bodies of water on the surface of the globe, the 

 remainder upon the land. Of the latter, part re-ascends in the form of 

 vapour, part is absorbed by the roots of vegetables, and part descends 

 into the bowels of the earth, where it forms springs. The only difference 

 between rain and spring water consists in the foreign particles which the 

 latter meets with and dissolves in its passage through the various soils it 

 traverses. Spring water being more pleasant to the taste, and more 

 transparent, is commonly supposed to be more pure than rain water. 

 Excepting distilled water, however, rain water is really the most pure we 

 can obtain : it is this which renders it insipid, whilst the various salts and 

 different ingredients dissolved in spring water, give it a species of flavour, 

 without in any degree affecting its transparency ; and the filtration it 

 undergoes through gravel and sand in the bowels of the earth cleanses it 

 from all foreign matter which it has not the power of dissolving*. 



When rain falls on the surface of the earth, it continues making its way 

 downwards through the pores and crevices in the ground. Several drops 

 meet in their subterraneous passage, unite, and form a little rivulet : this, 



