THE FARMER'S MAGAZINE. 



105 



THE DIFFERENT SYSTEMS OF DRAINAGE, 



^Ve are sometimes told that farmers ought to leave 

 their hubits and prejudices at home, and come to the 

 discussion of an a^ricaltural subject, exactly as a lob- 

 ster would if divested of its shell. Let us see how much 

 a meetinjj comlucted on such terms would be worth. 

 Th2 cultivation of a dark, strong, homogeneous clay, 

 affected entirely by water on its way from the heavens 

 downwards to the sea, and where tlie principle has 

 been to remove this as quickly as could be effected by 

 open parallel furrows on the surface, a few feet distance 

 only iipart, and intersected by parallel open drains, 

 in a cross direction, some 20 or 30 yards asunder. 

 Such a system with one man is the only drainage that 

 he requires to effect his object. 



The cultivator fiom another district (probably the 

 oolitic), where the soil is a dark tenacious clay at top, and 

 an open, porous, or absorbent soil below, is satisfied with 

 any depth of drain, provided it is deep enough to pene- 

 trate tlie retentive soil lying above, so as to give the 

 water free admission to the porous sub'^oil below. 

 Another, who lives in a district of greatly undulating- 

 surface — with a porous subsoil on extensive or dislo- 

 cated portions, and intersected at all angles with beds of 

 tenacious clay lying at various depths and thickness — 

 the porous portion supplied and overcharged with 

 water, endeavouring, by its own gravity, to force its 

 way through it from the highest to the lowest level, 

 and constantly endeavouring to escape upwards from 

 its disposition to find a level, or rising to the surface 

 by capillary attraction whenever the disintegrated par- 

 ticles rest on quicksands below, already highly charged 

 with water — the resident in such a district says that 

 nothing but dcep-dvainm'^ will answer, the distance 

 apart being only secondary ; but nothing less than 

 four-feet drains, and in many instances even twice that 

 depth, will suffice to rid the subsoil of its injurious 

 occupant. 



Again, we have the farmer from a country where 

 one uniform flat surface prevails, and regularity of 

 subsoil, are each of themselves equally remark- 

 able features; and he requires drains as near 

 to each other, in point of distance, as can be 

 effected — G yards apart at most, and from 26 to 

 30 inches in depth, running parallel to each 

 other throughout the whole field. This mode he 

 his found to answer his purpose, and he has no doubt 

 will equally answer for everyone else. 



And thus might we multiply instances without end. 

 But as a few invai'iable and unerring principles are 

 connected with the subject, we will endeavour to re- 

 cord them. 



1st. The specific gravity of water is 817 times heavier 

 than air. 



2iid. By its gi-avity it always has a disposition to 

 descend ; but the instant it meets with resistance it 

 . exerts its force equally in every other direction. 



3rd. That force is invariably exerted until it has found 

 a level, and it can then only be said to be at rest. 



4(h. Tiiat whenever this equilibrium is attained, it 

 remains in that state (stagnant) until disturbed. 



.'ith. That in perforating the t^oil with a drain, that 

 portion nearest the drain is first set in motion, and 

 this is followed in successive rotation by the next 

 nearest portion, and so on to the extent of its action. 



Gth. That its action ceases wherever the compact- 

 ness of the soil is sufficient to overcome the gravity of 

 the water held in it by suspension. 



0th. That water not only descends by its specific 

 gra\«ity, but ascends by capillary action ; wherever the 

 lower portion of the soil rests in water, the complete 

 disintegration of its particles facilitate that object. 



7th. That water passing from a higher to a lower 

 level through the soil, always has a tendency to rise to 

 the surface, and would invariably do so unless inter- 

 cepted by open or underground drains — hence the 

 origin of springs. 



8th. Water, on reaching the surface of the earth, 

 would continue to descend in the soil until resisted, 

 which it iuvariably would be whenever a porous soil 

 was preceded by a retentive one. 



9th. That water in its purest state, as rain water, is 

 slightly charged with ammonia ; but to an inconsidera- 

 ble extent, excepting after long seasons of drought. 



10th. That water becoming stagnant in a soil, be- 

 comes deleterious to plants growing upon the surface, 

 the mineral deposits, especiidly iron, after entering 

 into its composition, rising towards the surface. 



11th. That water passing through a hollow pipe 

 meets with resistance produced by friction. A pipe 

 filled at one end cannot be made to run full at the 

 other. 



12th. That water in a drain, upon meeting with re- 

 sistance, will fill it continuously upwards until the 

 weight of the column of water overcomes such re- 

 sistance by the pipes giving way at the lowest point. 



13th. That the velocity with which drains discharge 

 themselves depends upon their inclination and the per- 

 meability of the soil. 



14th. The specific gravity of water b. ing greater than 

 that of air, it invariably displaces the latter in the soil; 

 but upon its removal, air again occupies the space ori- 

 ginally held by it, and thus a continuous action is pro- 

 duced in the soil. 



15th Water when frozen expand<», and thus, by its 

 power, the hardest substances become broken up, or 

 have their external surfaces abraded by its action. 



The forego!no is merely a statement of those princi- 

 ples which will ever be coming into operation during 

 the processes of draining; and by observing'which the 

 operator can seldom err. Of all scientific practices, 

 that of draining is of itself the simplest of application; 

 the merely perforating the subsoil with a hollow 

 drain, at a sufficient depth must necessarily draw off 

 the accumulation of water held in suspension in the ad- 

 jacent soil. If this be tenacious, from thirty to thirty- 

 six inches, in most cases, will be sufficient, keep- 

 ing in mind that, although a greater depth might be 

 desirable, the cost of the drainage ought al- 

 wajs to govern the proceeding. On the con- 

 trary, if the subsoil is porous and charged with water, 

 flowing from a higher level, then the drains must be 

 sufficiently deep to carry off the water, that the soil 

 near the surface may not be rendered wet by capillary 

 action, bearing in mind that the more complete 

 and minute the disintegration of the soil, the greater the 

 disposition of the water from below to ascend towards 

 the surface. In some cases drains from forty to fifty 

 inches will be requisite. 



In soils alternating in quick succession of beds of 

 gravel, sand, and clay, a tow deep drains judiciously 

 placed will generally effect the drainage of large por- 

 tions of a field, remembering that the diain should 

 always be cut so as to intercept the water passing in 



