71 



branch connecting with a twelve inch cast-iron pipe leading around the 

 hase of Look-out Hill to the uppermost of a series of pools. This pipe 

 delivers the water at an elevation of one hundred and twenty-four feet, 

 and will be used when a supply of water is to be furnished to the pools 

 and cascades situated in the Ambergill and jSTethermead districts. 



It will thus be seen that the water from the well can be delivered at 

 elevations of sixty-one, one hundred and twenty-four, or one hundred 

 and sixty-feet, as the case requires, thus reducing the work and cost of 

 pumping to its minimum. 



The water from the Reservoir will be taken into the pipe distribu- 

 tion system to be used at the hydrants, drinking fountains, &c, at dif- 

 ferent points on the Park. This will constitute but a small proportion 

 of the water required on the Park. By far the largest quantity will 

 be required to supply the loss from the lake, due to evaporation from 

 the surface and leakage from the bottom. This water may be used to 

 produce pools, cascades, rapids, and running, brooks before it empties 

 into the lake. 



SOURCE OF WATER SEPELT EOE THE WELL.. 



The ground on that portion of the Park lying south of the hills, and 

 in fact all of the south side of Long Island is one vast bed of sand, 

 which is generally covered by but a few feet of soil and loam. On account 

 of this peculiar formation, a large proportion, probably sixty per cent, 

 of the rain fall is absorbed and passes down to what is popularly known 

 as " the main spring." This is a body of water filling the sand and 

 extending under this whole district. The distance from the surface of 

 the ground to the surface of this body of water depends upon the mod- 

 ulation of the ground ; but the elevation of this water surface above 

 tide level is quite uniform for equal distances from tide water, and de- 

 pends upon that distance ; it rises about seven feet per mile — so that, 

 for instance, at any point two miles from tide water the surface of this 

 subterraneous reservoir will be about fourteen feet above tide level- 

 The slope being known, it becomes an easy matter to calculate with 

 great certainty the quantity of water which can be obtained from the 

 well. 



The rain fall averages something over forty inches per annum, but 

 assuming it to be forty inches, then sixty per cent, of this, or twenty- 

 four inches in depth of water will reach the main spring. This quan- 

 tity over a circle with a radius of one half a mile will give a daily sup- 

 ply of about nine hundred thousand gallons. To draw this supply of 

 water to the well from a distance of one half a mile it will be necessary 



