DRAINAGE. 97 



some ditch or other superficial outlet. At 18 inches, 

 attraction will, on the average of soils, act with consider- 

 able power. Here, then, you have two obnoxious principles 

 at work, both producing cold, and the one administering 

 to the other. The obvious remedy is, to destroy their 

 united action ; to break through their line of communica- 

 tion. Remove your water of attraction to such a depth 

 that evaporation cannot act upon it, or but feebly. What 

 is that depth ? In ascertaining this point we are not alto- 

 gether without data. No doubt depth diminishes the power 

 of evaporation rapidly. Still, as water taken from a 30- 

 inch drain is almost invariably two or three degrees colder 

 than water taken from 4 feet, and as this latter is gene- 

 rally one or two degrees colder than water from a conti- 

 guous well several feet below, we can hardly avoid drawing 

 the conclusion that the cold of evaporation has consider- 

 able influence at 30 inches, a much-diminished influence 

 at 4 feet, and little or none below that depth. If the 

 water table is removed to the depth of 4 feet, when we 

 have allowed 18 inches of attraction, we shall still 

 have 30 inches of defence against evaporation; and we 

 are inclined to believe that any prejudicial combined 

 action of attraction and evaporation is thereby well guarded 

 against. The facts stated seem to prove that less will not 

 suffice. 



So much on the score of temperature ; but this is not all. 

 Do the roots of esculents wish to penetrate into the earth 

 at least, to the depth of some feet ? We believe that they 

 do. We are sure of the brassica tribe, grass, and clover. 

 All our experience and observation deny the doctrine that 

 roots only ramble when they are stinted of food ; that 6 

 inches well manured is quite enough, better than more. 

 Ask the Jerseyman ; he will show you a parsnip as thick 

 as your thigh, and as long as your leg, and will tell you 

 of the advantages of 14 feet of dry soil. You will hear 

 of parsnips whose roots descend to unsearchable depths. 

 We will not appeal to the Kentucky carrot, which was 



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