be done on the Fifth Avenue, between Fortieth and Twenty-first streets ; their contract with John B. Chollar and Ebenezer Jones, made the twenty-third of Octo- ber, one thousand eight hundred and forty, for iron pipe ; their contract with S. V. Mer- rick and John Town, for seven hundred tons of thirty-inch iron pipe ; and also their con- tract with T. H. Wintersteen and David I. Myers, for five hundred tons of iron pipe ; all which said contracts are deposited in the office of the Comptroller of the city of New York. The relative rights and duties of the parties being thus authoritatively settled, each proceeded, in his own sphere, to accomplish the matter in hand. It being strenuously desired that the city should, in the summer of 1842, be in the possession and enjoyment of the water, every effort was made to ensure such a result. Obstacles, however, arising from the great difficulty of the principal operations yet unfi- nished, disappointed partially, the hopes of the engineers and Commissioners. The contractors for the new dam in the Croton, for instance, were bound to have it in such an advanced stage by 1st November of this year, as to throw two feet water from the lake into the aqueduct. The next disappointment was in the bridge over the Harlem, arisin g from not finding, as the soundings had indicated, a rocky bottom on which to rest the foundation of some of the piers of the bridge. Nevertheless, the Commissioners and the engineers still adhered to the opinion that the 4th of July, 1842, would witness the intro- duction of the Croton into the houses and fountains of the city. The Report of the Commissioners on 17th of January, 1842, thus exhibits the state of the work : CROTON AQ.UEDUCT. Of the first division, the aqueduct part is finished, and was nearly so on the 1st of January 1841. The only part of this division remaining unfinished, is the dam. After the carrying away of the earthen embankment, comprising a major part of the dam, the undersigned concurred with the engineers in the advantage of constructing the new dam on an entirely different plan from the one previously constructed ; and instead of the extended earthen embankment, a continuous stone dam, laid in hydraulic cement, was decided on ; to be constructed entirely across the river, so that the overfall, or apron of the dam, will be of the same extent as the natural breadth of the river. The length of the new part of the dam (the mason work of the old dam not having been carried away) is 180 feet; so that with the mason work of the first erected dam, which still remains, it will make a dam of an overfall of 260 feet. The dam, when completed, will be about 50 feet high, having a base of masonry 65 feet wide ; and banked in, on the up stream side, with an em- bankment 250 feet wide at base. The profile of the face of the dam corresponds with the curved form which the water will assume in pouring over it, and is coped with cut stone, in the most substantial manner. At the toe of the dam, a heavy apron of crib work, 8 to 12 feet deep, and 53 feet wide, filled in with stone and planked, gives great security to that part of the work. With the view of keeping 4 feet of water on the apron at the toe of the dam, and thereby breaking the force of the fall, by its action on a body of water, there has been constructed, at a point 300 feet below the main dam, a secondary dam of timber and stone, which is 200 feet long and 9 feet high. The abutments of this secondary dam, with two piers of crib work, filled in with stone, have been used for the purpose of a bridge across the river, and will remain a bridge to accommodate the public and for the use of the keeper of the gate house. The construction of the new dam was vigorously commenced by Messrs. McCullough, Black & Co., early in the spring, under contract, to raise the same so high by the 1st of November following, as to throw at least two feet of water into the tunnel of the aqueduct. This requirement of their contract they have not fulfilled ; which is to be regretted, mainly on the ground that the work could not be left in as secure a condition against the spring floods, as it would have been left, had this condition of the contract been complied with. The contractors urged in excuse, the great difficulty in procuring sufficient quan- tities of large stone, and