630 TRANSACTIONS OF THE 



stumps as projected much above the surface, and levelling up the 

 lower parts with such materials as could be obtained from shallow 

 ditches excavated at the sides. In this way the bed was raised 

 from 4 to 6 inches above the general level of the marsh ; on this 

 was laid a flooring, of two inch hemlock plank, about eight feet 

 in width, and in some parts of double thickness, the planks 

 crossing each other at right angles. The pipes laid upon this 

 have remained in good condition, notwithstanding a trifling set- 

 tlement of the line in some parts. At Hackensack river a narrow 

 bridge about lOUO feet in length was built, upon wliich a box, 

 made of timber six inches in thickness, strongly bolted and trussed, 

 was laid to receive the pipes, which are furnished with what is 

 technically termed a slip joint near each end of the bridge, for 

 the purpose of preventing the lead joints from being destroyed 

 by the contraction and expansion of the iron, caused by changes 

 of temperatiu-e. As the Hackensack is a navigable river, it was 

 of course necessary to provide for the passage of vessels through 

 the bridge. This was done by sinking about 60 feet of the box and 

 pipes, opposite to the draw in the adjacent turnpike bridge, to 

 12 feet below low water, which places the whole completely 

 out of reach of the keel of every vessel that navigates the 

 river. 



The diameter of the pipes used for this inverted syphon, is 24 

 inches, the larger size being adopted to compensate for the obstruc- 

 tion to the flow, caused by the four changes of direction which 

 the water receives in passing through the syphon. The distance 

 between the two reservoirs is nearly six miles, and the difference 

 of level of the water in them is generally about 25 feet. With 

 this head, the 20 inch pipe will deliver into the distributing 

 reservoir a little more than 2,000,000 imperial gallons in twenty- 

 four hours, the quantity that would be raised by working the 

 engine eight strokes per minute for twelve hours, a rate at which 

 it may be worked if a proper stand pipe is erected. This addi- 

 tion to the works will, no doubt, indeed, must^ be made as soon 

 as the increased demand for water requires more than can be 

 raised by working the engine constantly at the present rate of 4^ 

 to 5 strokes per minute, a rate which, with the present arrange- 

 ment, cannot be exceeded with safety, because the water being 

 sent from the pump directly into the rising main, the friction and 

 inertia of a column 2305 feet in length must be overcome, and 

 the whole set in motion at each separate stroke. This slow rate 

 of working, however, is favorable to economy, the duty obtained 



