806 



WATER WORKS. 



for engine No. 2, 2,070,808 Ibs. Duty in Ibs. 

 raised one foot high per pound of coal, for en- 

 gine No. 1, 526,936 feet Ibs., and for engine 

 No. 2, 555,628 feet Ibs. 



The water is raised about 163 feet into the 

 Ridgewood Reservoir, a double reservoir, con- 

 structed with earth banks whose inside slopes 

 are lined with stone laid in cement. 



The area of water surface is of the 



Eastern Division Hi acres. 



Western " 13* " 



Total water area 25| acres. 



The height of the surface of the water, when 

 the reservoir is full, or the water 20 feet in 

 depth, is 170 feet above the Navy Yard high 

 water mark. The total capacity of this reser- 

 voir, when full, is 161,000,000 gallons. 



From the Ridgewood Reservoir the water is 

 conveyed to the city by a single 36-inch main. 



For the supply of a portion of the city above 

 the level of the Ridgewood Reservoir, another 

 engine has been erected at Prospect Hill, with 

 a reservoir at the summit, with earth embank- 

 ments and brick and cement lining. Its area 

 of water surface is 3 j acres ; depth of water, 

 20 feet; capacity, 20,036,558 N. Y. gallons; 

 height above mean tide, 198 feet. No dis- 

 tributing pipes are yet laid from this reservoir, 

 but it is kept full as a store reservoir 

 against accident to other parts of the work 

 which might reduce the supply or diminish the 

 head in the mains. The engine supplying 

 this reservoir is represented in outline in 

 (fig. 2). 



The engine is of the crank and fly-wheel 

 variety. The steam cylinder, S, is fitted with 

 slide valves, and a cut-off controlled by a gov- 

 ernor. The pumps are constructed on the same 

 general principles and mode of action as the 



FIG. 2. 



pumps at Ridgewood. They are 2 pumps at- 

 tached to opposite sides of the working beam; 

 they have valves in their buckets, and in chan- 

 nels at the sides of the pump. The pumps are 

 placed in a branch main, and the water flows 

 into and through the pumps under a considera- 

 ble head, variable with the draft upon the 



mains in other parts of the city. There are 2 

 air chambers : one shown at fi on the rising 

 main, the other, and a somewhat larger one, is 

 connected by a branch pipe with the induction 

 pipe at E. At A are the connections with the 

 air pump. At p the connections of a small sin- 

 gle-acting plunger pump to supply the boilei 



