of the vast sums that would be expended, and of various and perplexing questions that could not fail to arise in the progress of the undertaking, in the shape of claims from per- sons supposing themselves aggrieved, by contractors for extra allowances, &c., &c, the Commissioners suggest, for the consideration of the Common Council, the adoption of a plan similar to that adopted by the State in respect to the construction of, and expendi- tures on, the canals, viz. : constituting two Boards, one, Commissioners of the Water Fund, to be composed of the Mayor, the Comptroller, the Counsel of the Board, the Street Commissioner, and the City Chamberlain, who shall have charge of all financial arrangements in raising and borrowing the necessary money, securely investing it until wanted, &c. ; the other, the Water Works Board, to consist of the Water Commission- ers and the Commissioners of the Water Fund, whose business it should be to adjust and settle all such claims and complaints as are above alluded to. On January 4th, the Commissioners made their next semi-annual Report, which, with its accompanying documents, is of great interest and importance. In the course of the autumn, contracts were made for the ten sections of the first division which were before unlet, and for 27 sections of the second division, making an aggregate of 53 sec- tions, which, with the dam, were to cost $2,823,691. A change, too, was made, on the recommendation of the chief engineer, in the posi- tion of the dam in the Croton ; a place about 400 feet down the stream being supposed more suitable for the purpose. This change led to another in the structure, lessening MEMOIR OF THE materially the mason work of the dam. The contractors availed themselves of the alte- ration to abandon their contract, and, accordingly, this portion of the work was re-let for $85,386, a saving over the first contract of $32,169. The difficulties interposed to the progress of the work by the opposition of the land- holders on the route, and the alarming stories spread of the lawless disposition and prac- tices of the laborers on the line, form a prominent subject of detail in this report, which insists, however, and successfully, as it seems to us, that neither drunkenness, nor robber- ies, nor abuse nor insult of casual visitors, could be traced to these laborers. Great delays, however, were occasioned by the slow process of appraising the lands, and the slower progress in confirming the awards by the Chancery Court ; and hence', it frequently happened, that when contractors had erected shanties and other buildings, and brought their teams and materials on the line, they were unable to go to work, because the lands were not as yet in the legal possession of the Commissioners. Nor could this have been foreseen by these officers, for every measure on their part had been taken to ensure prompt settlement of the appraisements. As keeping up the record of the progress of the work, we subjoin the statement of this year's work : The following statement comprises the principal portions of the work which have been performed during the last season, say from the first day of June to the first day of December last. Two thousand four hundred and fifty-five feet of the aqueduct is now complete. There have been erected also about 400 feet of inside wall of the aqueduct, ready for springing the arch. The amount of open cutting and excavation in earth, is 146,760 cubic yards, and the same description of work in rock is 18,272 cubic yards. The tunnellers had penetrated the rock four hundred and six feet on the first of De- cember, and on the first of January, inst., they had extended the work to 653 feet. It is confidently anticipated that several of these tunnels will be completed during the present winter, the work progressing through the intervention of a relay of hands both day and night. The tunnel under contract to Scott & Young, in the village of Sing Sing, is now within a few feet of seeing daylight through it, and a short tunnel of 150 feet under con- tract to T. N. Ferrell, is cut through from end to end. Six of the culverts are completed, and five partly finished. They vary in dimen- sions from two to ten feet span of the arch, and from 50 to 150 feet , in length. The inverted arch or floor of the incomplete culverts is finished, so that the flow of water through the brook, passes them freely ; and sufficient of the upper arch has been laid to permit the crossing of the valley with the stone embankment. The foundation wall of the aqueduct, amounting to 12,050 cubic yards, and