FARM EXPERIENCE. 253 



drain should always be continuous. The height of the spring 

 should be estimated, and it should be carried down with one 

 uniform slope, never for one instant rising above the slope. 

 As far as possible, a drain should be straight, or, if tiiat is 

 impossible, the curves should be as large as possible, never 

 sharp. It is horizontal and vertical curves which prevent 

 the efficiency of drains. 



I have seen with my own eyes cases where the temperature 

 of the soil has been raised twelve degrees by putting in a 

 drain. That is equivalent to the difference in latitude which 

 exists between Connecticut and South Carolina. Who can 

 overestimate the advantage of such an increase in tempera- 

 ture ? Again, when the ground is saturated with water, it is 

 utterly impossible for those chemical transformations which 

 are indispensable to the liberation of the soluble materials of 

 the soil to go on. When the oxygen of the air is prevented 

 from access to it, by saturation with water, it is impossible 

 for the carbonic acid to be generated, or the hiimic acid, 

 which is necessary for the solution of the mineral matters. 

 The first thing, therefore, to be done, is to drain thi§ off. 



Then, again, in many cases, there is as much advantage from 

 the air which circulates through the drain, as there is from 

 tlie water that goes off. In the first place, the air which cir- 

 culates through an underdrain, penetrates upwards as well as 

 downwards, and the ground is aerated in a remarkable man- 

 ner. 



Again, lands vrhich are underdrained can withstand 

 drouths a great deal better than those which are not drained, 

 because, the drains being cooler than the upper por- 

 tion, the air which is circulating through it, deposits dew on 

 the interior of the tiles, which is absorbed by the ground, and 

 in this way that extreme aridity wdiich sometimes takes place 

 is prevented altogether by this action of the underdrain upon 

 the air which circulates through it. 



There is another point to which I wish to refer, and that 

 is the necessity of varying the food of cattle. Cattle are 

 never satisfied, even with the very best ; a change once in a 

 while to an inferior food will be found to be highly satisfactory 



