GROUND OPEEATIONS. 



146 



turc, provided the hot water is poured on the top for 

 a sufBoient length of time. The undrained land is 

 the mixture of drowned mud ; the water in posses- 

 sion, hy its mere superior weight, successfully resists 

 the entrance of the lighter and warmer water. The 

 drains are the opened stop-cocks, and these, once 

 opened and kept open, allow the warm rain-water to 

 percolate freely through the entire mass of soil, and 

 thus raise its temperature to the level of the warm 

 summer showers. 



Nor are these views theoretical only. The rise of 

 the general temperature of earth hy drainage has 

 heen proved by direct experiments to he so very 

 considerable as from five to fifteen degrees. It is 

 impossible to estimate the enormous importance of 

 such increased temperature on horticultural pursuits. 

 A rise of ten degrees, or even five, in not a few 

 gardens would make all the difference between the 

 possibility or impossibility of growing or not grow- 

 ing such semi-tender fruits as peaches, nectarines, 

 and apricots in the open air. And so also of any 

 other garden crops, in which success or failure very 

 often depends upon an increase of from two to five 

 degrees of heat. 



Besides, water-logged land is almost as cold in 

 summer as in winter. Supposing the temperatm-e 

 of the stagnant water to be forty-four or forty-five 

 degrees, the thawing of snow-water in the spring 

 may probably reduce it to forty. Such water will 

 prevent any summer rain from entering ; hence the 

 soil throughout the year remains almost of the same 

 uniformly low temperature. And thus, while the 

 tops of plants are being forced into vigorous gxowth 

 by the genial heat of the summer air, the roots are 

 chiUed in earth not much more than eight or ten 

 degrees above solid ice. It is little wonder that 

 .imder such conditions the plants refuse to thrive, and 

 the produce of gardens is inferior or worthless. Of 

 course, drained lands are subject to greater altera- 

 tions of temperatm-e than those that are undrained ; 

 hut this is a decided benefit to be desired, not an 

 evil to be shunned. The nearer within reasonable 

 limits the root and top temperatures can be assimi- 

 lated, the better for the plants. Thoroughly drained 

 lands are, on the whole, of a higher temperature than 

 the air ; but the tendency is towards equality. The 

 absorption of the sun's heat, the penetration of 

 summer showers, the warm delugings of thunder- 

 storms, all tend to keep the earth in summer as warm 

 or even warmer than the air. Taking the average 

 mean temperature of the air at any given place, the 

 heat of the earth on good soils will mostly be found 

 to exceed that of the atmosphere by five or more 

 degrees. A good deal, however, depends upon the 

 colour and texture as well as the drjmess of soils. 

 Dark-coloured soils heat and also cool the soonest ; 

 10 



while it is almost impossible for light soils to be 

 warmed at all, especially if they are wet. 'Ihsse 

 differences in the character, condition, and colouring 

 of surfaces would have almost as much influence on 

 the acceleration or retarding of crops as the tempera- 

 ture of the surrounding air, while the latter is also 

 raised sometimes as much as ten or fifteen degrees 

 by the mere act of draining wet land. The general 

 climate of the Feus and other low-lying districts has 

 been so much improved by drainage, as not only to 

 double or treble the produce of the land, but to add 

 greatly to the average length of human life. 



Drainage also Sets Free, Distributes, 

 and Adds to the Kichness of Soils.— "Water in 

 motion is one of the most powerful distributing and 

 carrying forces or agents. It has left the marks of 

 its handiwork in beds of clay, gravel, and alluvial 

 deposits of the richest character all over the world; 

 It carries on the same kind of work, though on an 

 infinitely smaller scale, in the smallest streamlets 

 as in the broad deep rivers ; that is, it breaks down 

 and re-distributes the most soluble, and therefore 

 the best, earthy particles it meets on its com-se. 

 Water is not only a warmer, but a worker. Its 

 cleaving force and solvent properties are wonderfully 

 unden-ated. Each water-drop channels or cuts its 

 own way towards the main or secondary di-ains. 

 Doubtless in this work it is considerably assisted 

 by earth-worms, moles, and other agencies. But 

 still the bare facts are as have been stated. 



But water is more than a mere mechanical worker, 

 and is as much at home in the chemical laboratory 

 as in the simple art of perfecting and extending the 

 miunte ramifications of collecting and feeding drains. 

 Water-logged land is in one sense like money in 

 an iron safe in a bank ; all its fertility is locked up, 

 but, unlike the money in the safe, its value rapidly 

 depreciates, and wiQ speedily be destroyed. This 

 latter consideration, however, does not affect the 

 present argument. Water, the only known or used 

 seal for our lighting-gas, also seals in the earth's 

 fertility. No matter how full of manure or growing 

 force it may be, neither the cultivator nor the 

 plants can utilise one atom of it till the water-seal 

 is broken or removed. Drainage breaks the seal or 

 opens the lock of the safe, sets free and augments 

 the natural or acquired fertility of the soil, and 

 links that fertility to vegetable life, and transforms 

 it thus into crisp vegetables, beautiful flowers, and 

 luscious fruits. 



In these great achievements and transformations, 

 water in motion and water as a solvent bears the 

 most important part. But water does not work alone. 

 For better or worse, water and air are linked to- 

 gether in the economy of the universe. They are cor* 



