Fourth Division, commencing at section 80, terminating the third division, and running to the Battery in the First Ward of the City of New York, distance in all fourteen miles. Of this division, sections 80, 81, 82, 83, 84 to 85, in length about two miles, are in Westchester County, and are entirely completed. The whole distance in Westchester County, all of which is nearly completed, is 32 miles and two-thirds of aqueduct, the arch bridge of 88 feet span at Sing Sing, 12 tunnels (or under ground excavations for the aqueduct,) whose aggregate length amounts to

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4406 feet, 32 ventilators for the escape of the air from the tunnel, and four waste weirs, for the discharge of the surplus water from the aqueduct.

The Harlem River Bridge. After leaving the sections of the fourth division in Westchester County, we arrive at section 86, which includes the crossing of the Harlem River, and here we have been engaged with the high bridge. We should be happy to be enabled to state, that this structure could proceed as rapidly as the remaining part of the work, and would be as soon completed. This bridge, it will be recollected, is, by the plan, to be supported by seven land arches, each of 50 feet span, on the valley between the river and the adjacent hills, and over the river by eight arches of 80 feet span each, the crown of the intrados of the arches is 100 feet above the surface of the water, and the height of the superstructure near 120 feet. We have sunk four coffer dams in the river for the river piers, and built the foundations of two piers to above high water mark, and another is about four feet above the foundation. The amount of money spent on the Harlem Bridge, for the work and materials not yet used, amounts to $91,100.