EARTH A DESERT WITHOUT CAPILLARY ATTRACTION. 33 



or pulverized. It is for this reason that subsoil plowing 

 becomes so eminently beneficia;!, by deepening the mellow 

 portion, and thus affording a larger reservoir, which acts 

 like a sponge in holding the excess of falling rains, until 

 wanted in the dry season. For the same reason, a well- 

 cultivated soil is found to preserve its moisture much bet- 

 ter during the heat of summer than a hardened and neg- 

 lected surface. 



If capillary attraction should cease to exist, the earth 

 would soon become a barren and uninhabitable waste. 

 The moisture of rains could not be retained by the parti- 

 cles of the soil, but would immediately sink pi jy 

 far down into the earth, leaving the surface 

 at all times as dry and unproductive as a 

 desert ; vegetation would cease ; brooks and 

 rivers would lose the gradual supplies which 

 the earth affords them through this influence, ^>- 

 and become dried up ; and all j^lants and all ^B 

 animals die for want of drink and nourish- ^SV ^^M 

 ment. Thus tlie very existence of the whole ^^L^^m 

 human race evidently depends on a law, ap- ^-~ ^ ^ 



.. .^ , ,.,. , Apparatus ex- 



parently insignificant to the unthinking, but plaining the 



. , , . . . T ... rising of sap. 



pointing the observing mind to a striking 

 proof of the creative design which 2:)lanned all the works 

 of nature, and fitted them with the utmost exactness for 

 the life and comfort of man. 



ASCENT OF SAP. 



The following interesting experiments serve to explain 

 the cause of the ascent of sap in plants and trees : 



Take a small bladder, or bag made of any similar sub- 

 stance, and fasten it tightly on a tube open at both ends 

 (fig. 17) ; then fill them with alcohol up to the point C, 

 and immerse the bladder into a vessel of water. The al- 

 cohol will immediately rise slowly in the tube, and if not 

 2* 



