feet across ; breadth at the bottom about seventy feet, and on the top or lip, seven feet, averaging about forty feet in thickness. The down stream course will slope one and a quarter to one, and the up stream will be carried plumb. The abutments twelve feet thick ; the top and down stream slope to be covered with heavy coping, well clamped together with iron anchors and straps, &c. In fact, the whole structure is to be a mass of substantial stone masonry, combined together with hydraulic cement and, when com- ;

pleted, will be one of the most stupendous erections of the kind to be found in any part of this or any other country.

The next important work in order, is the Aqueduct Bridge, across the valley of Sing Sing Kill. This requires an arch of eighty feet span and twenty-five feet rise, resting on abutments of stone masonry, and is intended to be a work of great strength and solidity. In addition to these, there are several large culverts to be built, for crossing the streams and brooks running through this section of the works some pretty lofty embankments ;

to be made, and four tunnels, of from 300 to 800 feet in length, through hills of more or less altitude.

The most prominent work on the second division, is the crossing Mill River, which must be effected, either by an aqueduct bridge, of heavy stone masonry, or by a large culvert and embankment, the latter of which the Commissioners have preferred. There are also two tunnels in this division, of considerable length, with a number of small culverts for crossing the several ravines and brooks on the line of the aqueduct.