37 



The earth in the Prospect Park consists, first, of a few inches 

 of soil, then a layer of clay, varying in thickness, sometimes 

 alternate layers of clay and sand, beneath which is hardpan or 

 drift. In the larger depressions, there is sometimes quicksand 

 beneath this, and scattered through the drift an innumerable 

 quantity of boulders, which defy the precise location of drains, 

 except on the ground itself. As a general rule, the main drains 

 should be from three to four feet below the surface, and the 

 lateral drains from two feet six inches to three feet. An increase 

 of depth adds largely to the expense, especially in the hardpan, 

 where it will cost almost as much to keep the picks sharp as 

 the labor is worth, and in the end adding, perhaps, no benefit 

 to the ground. Still, no question of economy should prevent 

 the drainage being thoroughly accomplished. 



The drain should be laid below the frost, and must be below 

 the reach of the sub-soil plow or trenching tools. The fact 

 that a large quantity of soil and fertilizing matter will be 

 added to the present soil, which is rather worthless in its 

 character, will govern somewhat the depth beneath the present 

 surface. 



DISTANCE BETWEEN DRAINS. 



There exists a positive relation between the depth of drains 

 and their distance apart — the tenacity of the soil being the 

 governing principle. The more retentive soils require the 

 drains to be nearer the surface and nearer together, say from 

 fifteen to thirty feet, while in porous soils the drains should be 

 deeper, and may be further apart, say from twenty to sixt} T 

 feet. The thorough working or trenching of the ground will 

 obviate the necessity of placing the drains as near to each other 

 as would be required to remove immediately the water now 

 present in the soil. When this, which now occupies the ground 

 so universally, is removed, that which falls afterward would find 

 in the soil, rendered porous by being worked, a ready outlet 

 through these drains, although they would have less immediate 

 effect upon the ground. 



The leading principles which have been enumerated, have 

 been followed out in the construction of the plan of drainage. 

 It is not deemed essential to enter into the details of digging 

 the trendies. If not done by contract, the lines of drains 



