144 INTRODUCTION. 



the work. Inside of the walls of masonry, a thorough puddled embankment of 

 suitable earth is formed, 58J feet wide at the line of the reservoir bottom, and 

 slopincf on the inside face 1 J to 1 per 24 feet high, and making, with the walls on 

 top, a width of 17 feet; the face of the banks is hned with a course of rubble 

 hydraulic masonry 15 inches thick, and coped with dressing stone. The bottom 

 is an impervious hardpan, on which two feet of puddled earth is laid, and this 

 covered by 12 inches of hydraulic cement. The reservoir is divided into two 

 divisions by a wall of hydraulic masonry ; the wall is 19 feet thick at the bottom, 

 6| feet at top water line, and 4 feet at the top. In this wall a waste-weir is placed, 

 with a well of two falls, together 52 feet, from which the waste water enters a 

 sewer and passes off about one mile to the Hudson. In each division there is a 

 waste cock to draw the water from the bottom. The reservoir is designed for 36 

 feet of water, and when full, will stand 115 feet above mean tide. The walls rise 

 four feet above the water line. An iron railing is to be placed around the walls 

 on the top of the cornice. The capacity of this reservoir is 20,000,000 imperial 

 gallons. 



The general declivity of the aqueduct is 0-021 foot per hundred, or a fraction 

 over 13^ mches per mile. The Croton reservoir, which has received the name 

 of Croton lake, is available for 500,000,000 imperial gallons of water, above the 

 level that would allow the aqueduct to discharge 35,000,000 gallons per day. 

 The flow of the Croton river is about 27,000,000 of gallons in twenty-four hours 

 at the lowest stages. The work was commenced in May, 1837, and so far com- 

 pleted that the water was admitted into the distributing reservoir on the fourth 

 of July last. The survey, plans and estimates of the work were made by pro- 

 fessor Douglass, who was succeeded as chief engineer by John B. Jervis. The 

 aqueduct has been constructed at the expense of the city of New- York, under 

 the direction and supervision of commissioners appointed by the governor and 

 senate. The following persons have been commissioners : Stephen Allen, Walter 

 Bowne, Benjamin M. Brown, Saul Alley, Charles Dusenbury, William M. Fox, 

 Thomas T. Woodruff and Samuel R. Childs. The present commissioners are, 



