The first line runs diagonally from 128th street in the 9th Avenue, to between 118th and 119th streets, in the 10th Avenue. The second line crosses the valley, and runs parallel with, and 125 feet from, the 10th Avenue. The third line continues through the centre of the 10th Avenue. The crossing of all these lines is to be effected by means of a bridge, with semicircular arches of 50 feet span. The length of the three lines from grade on the north, to grade on the south side of the valley, are as follows :

- First, or diagonal line, 3,300 feet. Second, running 125 feet east of10th Avenue, - - 3,700 feet. Third line, running through the 10th Avenue, 3,700 feet.

The maximum elevation of the bridge above the natural surface of the ground to grade line, is about 103 feet, and to the top of the parapet wall 116 feet. To erect a bridge on the first or diagonal line, as per estimate, will cost $983,000 00 The same for the second line, - 1,286,880 00 The same for the third line, 1,286,020 00

$3,555,900 00

It thus appears that making an average of the cost of crossing the valley on an arched bridge, by the three lines designated, and continuing the aqueduct on its regular inclination, will amount to $1,188,633. An estimate is then presented, for crossing the valley with pipes, or inverted syphons, of three feet diameter. The estimate proceeds upon the principle, that only two pipes will be required at present, which will supply about nineteen millions of gallons per day, and allow thirty gallons to each person, of a population of 600,000 inhabitants and in ;