170 IMPOETANCB OF DBAINAQE. 



The removal of superfluous water by drainage lias been 

 already shown to be attended by an elevation of earth-tempe- 

 rature (see p. 137). Its other efi'ects, of taking out of land 

 the water which plants cannot assimilate (and no more), and 

 at the same time of enabling rain water charged with salts 

 of ammonia, a direct food of plants, to reach the roots with 

 every shower, probably constitute the whole rationale of this 

 important operation. 



In bibulous soils lying high this contrivance may be unne- 

 cessary ; but in those which are tenacious, or which, from their 

 low situation, do not permit superfluous water to filter away 

 freely, such a precaution is indispensable. No person has ever 

 seen good crops produced by trees growing in lands imperfectly 

 drained; and aU experienced gardeners must be acquainted 

 with cases where wet unproductive borders have been rendered 

 fruitful by contrivances which are chiefly valuable because of 

 their efficiency iu regulating the humidity of the soil. 



Such preoautiona as are detailed in the foUowing good accotuit of 

 preparing a Vine border, stow how important it is to provide effectually 

 for the removal of superfluous water from roots, and how useless a waste 

 of money is that which is expended in forming deep rich beds of earth. 

 " In preparing a Vine border," says Mr. Griffin of "WoodhaU, a success- 

 ful grower of Grrapes, "one foot in depth of the mould from the surface 

 is cleared out from the whole space ; a main drain is then sunk parallel 

 to the house, at the extremity of the border, one foot lower than the 

 bottom of the border ; into this smaller drains are carried diago,naUy 

 from the house across the border. The drains are filled with stone. 

 The cross drains keep the whole bottom ciuite dry ; but if the subsoil be 

 gravel, chalk, or stone, they will not be necessary. The drainage being 

 complete, the whole bottom is covered with brick, stone, or lime rubbish, 

 about six inches thick, and on this is laid the compost for the Vines." 

 {Hort, Trans., iv. 100.) This is in accordance with a practice well 

 known in vineyard countries. "In France, in the Vine districts, where 

 water frequently collects in great quantities at a certain depth in the 

 earth, the trees are planted upon an under-layer of stones, which are 

 covered with earth, and in this manner the roots are kept from too much 

 moisture, and the water is drained away.'' {German Translator.) 



The practice of placing large quantities of potsherds or 

 broken tiles at the bottom of tubs, or pots, or other vessels in 

 which plants are rooted, is only another exemplification of the 



