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.

In the third division, the crossing of Saw Mill River and Tibbit's Brook occurs, a pretty formidable part of the work. There are two tunnels one at Yonkers, for entering ;

the valley of Saw Mill River, and the other for entering the valley of Tibbit's Brook.

The fourth division embraces some highly important works. The most imposing is the crossing of Harlem River, either by an aqueduct bridge, or by inverted syphons ;

next, carrying the aqueduct over Manhattan Valley ; and last, though not least, the erection of the receiving and distributing reservoirs in this city.

Here we have a formidable array of work, to exercise the talents of our chief engineer, in planning, and the ingenuity of our mechanics and laborers in executing and if ;

to this be added the great length of the aqueduct to be built, and the large amount of excavation to be effected, in many places from fifteen to thirty feet in depth, and that through a soil abounding with rock, stone, and cemented earths, it cannot be wondered at if the estimates of the engineers, originally employed to make the necessary examinations shall fall far short, as the Commissioners have now good reason to think they will, of the sum