The quantity of water was extremely small, in some cases not sufficient to make a perceptible stream in the channel designed to carry any leakage that might occur to the sewers on the outside, but the earth was fully saturated, and in other cases a very small trickling stream passed off in the channel. The extent of this leakage is small, the main part of the bottom appearing well. The leakage through the interior walls is very small they are as impervious as could have been anticipated, in view of the great pres- ;

sure to which they are exposed. Their greatest leakage is at the junction of the division walls with the influent and effluent cock vaults. In each direction from them, the leakage decreases, and in about half of the western division the walls (and channel to carry off leakage water) are entirely dry. There is conclusive evidence that the leakage through the walls has to some extent subsided, although the pressure, by gradually raising the water, has been increasing. The water now stands in the reservoir at about thirty-three feet above the sills of the gate frames, or thirty-five feet above the bottom, and within three feet of the designed top water level.

Some small leakages have occurred in the joints of the iron pipes, that have been laid down in connexion with the aqueduct work the most troublesome has occurred in ;

the temporary pipe at Harlem River, and is mainly to be attributed to the manner in which it was necessary to lay down this pipe, not allowing all the freedom of action that is necessary to provide for the expansion and contraction occurring in the different temperatures to which they are exposed. The aqueduct and its appurtenances have been subjected to the trial of near seven months, and I have endeavored to detail fully the effect the water has produced, and the prospect of its capacity to fulfil, with regularity and permanence, the object of its construction.