We are thus particular in giving the names and stations of the engineers, because in so grand a work, and which, so far as yet tested, has proved so thoroughly well constructed, it is though in comparatively subordinate stations, conjust that they who, tributed largely to its excellence and sufficiency, should be commemorated.

The Commissioners present this brief but clear sketch of the respective divisions of the aqueduct line, and of the great natural difficulties to be overcome ;

146 MEMOIR OF THE The country through which our line of aqueduct lias to pass, affords, perhaps, as few facilities for the avoidance of labor and expense as any other portion of the State ;

we are met at every step with deep ravines, which must be passed, either by embankment or bridge, or elevated hills which must be pierced by a tunnel of more or less extent. The most prominent objects of labor and cost on the first division are r first, the dam across the Croton River. This dam will be fifty feet high, from the bed of the river, and about forty feet from low water level the top, or lip of the dam, about one hundred ;

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- ;