spectator with the belief that it is almost, if not entirely, indestructible by the elements, or time. Between the Croton Dam and the influent gate-house at Harlem River, the line of aqueduct was finished last season, and during the present season this gate-house has been nearly completed. The embankment in the Harlem River, which serves the double purpose of securing the cofferdams for the piers of the bridge, and forming a foundation for the temporary 49 194 MEMOIR OF THE water pipes, has been finished, and the pipes were laid upon it, and a connection formed between the two sides of the river early in June. To the lowest part of the large connecting pipe, a branch pipe was attached, and to this were fitted jets of various sizes and forms. This was done for the purpose of ascer- taining by experiment, what form and size will be best suited for fountains, which may be erected in the public squares or other parts of the city, for convenience or ornament. The jet is generally allowed to play a few hours in the afternoon of every day, and the large volume which it throws to the height of 110 feet, is an object of much interest to those who visit this, at present, most interesting spot. HARLEM RIVER BRIDGE. — The progress of this work, since our last report, has, owing to several causes, been slower than we expected. In that report it was mentioned that after carrying the excavation for pier No. 10, thirty-four feet below the surface of the water, without finding rock, it was determined to place it upon piles. In carrying out this determination, 240 bearing piles have been driven, varying in length from 30 to 36 feet. Cross timbers were laid upon the heads of these, and the spaces between these timbers filled with concrete. Upon the timbers, the cut stone masonry was commenced, and several courses of this are now laid. All the difficulty and danger inseparably con- nected with the use of coffer dams, of the great size and depth required for this pier, have been successfully overcome, and the masonry will, in a few weeks, be raised above the high water of the river. The coffer dams for piers Nos. 11, 12, and 13, are in their places, and embanked, but none of them have yet been cleared of water, or the character of the foundations ascertained. It is expected, however, that 11 and 12, and perhaps 13, will require the same operations of piling and timbering, previous to laying down any part of the masonry. The present condition of the work is as follows : The foundations of piers Nos. 2, 3, 4, 5, 6, 7, 8, 9, and 10, are laid and secured, and the masonry of all, except No. 10, is carried above high-water mark from 4 to 15 feet. The foundations of Nos. 11, 12, and 13, which are river piers, remain to be put down, and Nos. 1 and 14 at the two ends of the bridge. These last will be built upon rock, and at a considerable height above the water. A very large quantity of cut stone, for various parts of the work, is prepared, and much of it brought upon the ground. All, or nearly all, the timber for the centres of the arches is delivered, and the amount of machinery and arrangements of the contractors for carrying on the work is such, that if the commissioners should feel authorised to urge it forward, there is no doubt but it could be carried up as fast as a due regard to its stability would warrant. RECEIVING RESERVOIR AT YORKVILLE. — The excavation at this place was carried on at a moderate rate during the whole winter, and on the opening of the spring, such additions were made to the force employed there, that the work was fitted for the recep- tion of water on 27th June. It is not yet, however, entirely finished ; but the contractors are making such pro- gress as will probably enable them to complete the whole in the course of the ensuing month. The work in the 5th Avenue, in which are laid the -iron pipes, connecting the receiving and distributing reservoirs, is nearly completed. Something remains to be done at one or two culverts, and perhaps something more ought to be done in the way of regu- lating the Avenue. DISTRIBUTING RESERVOIR AT MURRAY'S HILL. — This work is now nearly com- plete ; about one-half the length of the enclosing wall is finished, and the remaining half CROTON ACIUEDUCT. 195 requires little to complete it but the cornice. So far as it has been tried by the pressure of water 20 feet in depth, it has proved perfectly