This gave an extra height ot -

side walls, enlarging the capacity of the aqueduct, more than equivalent to the diminution of declivity, and provides for drawing -from the reservoir to a depth of 6 feet, and still leave the capacity of the conduit 35,000,000 of imperial gallons.

The grade of the aqueduct from Harlem river to Manhattan vfilley. is the same as the general declivity in Westchester county but that from Manhattan valley to the re- .;

It has been stated^ the extra fall ceiving reservoir 2.1727 miles, is 9 inches per mile. given for the pipes at Harlem river, is 2 feet, and at Manhattan valley 3 feet between the ;

reservoirs there is a fall of 4 feet, when both are full but it is expected something more ;

than this will be required at times, to furnish the full quantity that will be wanted. The pipes are provided .with waste cocks at the depressions, and air cocks at the summit bends. The first contracts for work on the aqueduct, were made in April, 1^37, at which <

time about ten miles of the upper end was advertised, but in consequence of the proposals being considered too high, only about half of it was contracted for. About the middle of May, the contractors generally entered on the work contracted for. In September following, about 16 miles more was put under contract in May, 1838, the balance of the ;

line to Harlem river was put under contract; and the work on the island, except the