The anchorage was commenced in September, 1852, and was formed by sinking 8 shafts into the solid limestone rock that here composes the uppermost stratum of the cliffs. This layer is solid for a depth of 14 feet, underlaid by a limestone shale, which again is followed by a solid stratum. Three of the pits on the New York side are sunk to a depth of 25 feet. The fourth one, south east, is only 18 feet, where the rock proved very solid and without any fissures. This shaft was not sunk deeper, on account of the great influx of water and difficulty of bailing. In consequence, the lowest link of that chain was omitted, and a greater hold given to the rest by reverse arches thrown against the knuckles, also by the introduction of crossbars. With the exception of this shaft, all their others, on both sides of the river, have been sunk to an equal depth, 54 feet below the railroad track. The surface of the rock on the Canada side being 10 feet higher than on the New York side, the depth of shafts was increased that much, and the height of the masonry above reduced in proportion. Each shaft has a cross section of 3 + 7 feet, enlarged at the bottom to a chamber of 8 feet square. The anchor chains are composed of 9 links, all of which are 7 feet long, except the uppermost or last one, which is 10 feet. The first or lowest link is composed of 7 bars, 7 + 14 inches, and is secured to a cast-iron anchor plate by a pin of 3 1/2 inches diameter, ground upon its seat. The next link is composed of 6 bars of the same size, and 2 half bars on the outside. The aggregate section of each is 69 superficial inches. From the fourth link on the chain curves, and the section is gradually increased to 93 superficial inches. Four of these chains were manufactured of the best quality of Pennsylvania charcoal blooms by Everson and Preston, of Pittsburgh, the other four were made at Napannock, Ulster Co., N.Y., by Mr. Frederick Bange. They were manufactured out of Salisbury pig, puddled in wood fire. Both these irons can be depended upon for a strength of 32 tons of 2,000 lbs. per square inch. I have tested them thoroughly by cutting up a number of extra bars and pins, and forging them over into various shapes. All the sockets attached to the ends of the wire rope suspenders and stays, which are very difficult to forge, and require the best quality of material, have been made of this Naponnock iron.

The tension of the different links composing each chain diminishes as they descend, the strain upon the vertical links being more than one-third reduced, in consequence of position, friction, and hold in the masonry. The lowest link is secured to a cast-iron plate of 6 feet 6 inches square, 2 1/2 inches thick at the edges, with 8 heavy ribs upon the lower side. The central portion through which the bars are admitted has a depth of metal of 12 inches. Where a seam in the rock offered a good chance to form a solid bed, one-half of the plate rests against it, and the other half against masonry. After securing the position of the plate and chain, the whole shaft was filled out with masonry laid in cement mortar and copiously grouted. Great care has been taken to grout the bars well. My experience has given me ample proof, that cement grout will take a firm hold of iron, and will effectually guard it against oxidation. The bars were well oiled with linseed oil, then painted twice with zinc paint and Spanish-brown. Where no solid face could be obtained, the roof of the chamber was cut out prismatically. The masonry resting upon the plate presses against this roof like a wedge. Large stones were laid upon the knuckles, so that every joint has a hold in the masonry, above as well as below the surface of the rock. Above the rock, where the chain curves, each knuckle rests upon a cast-iron plate, bedded upon a large cut stone. This again rests upon one still larger, or upon two flat stones, which distribute the pressure upon the masonry below. No labour has been expended upon the face work of the anchor-walls, but the inside has been faithfully executed to insure a strong job.

The aggregate section of the upper links of the four chains is 372 square inches, and their ultimate strength, at 32 tons, equal to 11-904 tons. The strain upon the lowest link is at least diminished one-third, which leaves 7,936 tons. This pressure on the New York side is resisted by a sheet of solid rock of no less extent than 100 feet long, 70 feet wide, and 20 feet deep. This rock weighs about 160 lbs. per cubic foot. Now, assuming only 200 lbs. of resistance in the solid rock, we have a mass of 140,000 cubic feet opposing a force of 14,000 tons, without taking into account the weight of the superincumbent masonry and embankment Admitting that the rock was full of fissures and seams, which is not the case, the entire safety of the anchorage is evident.

The great and very sudden changes of temperature to which this locality' is exposed, and also the intense cold sometimes experienced in winter, made it necessary to enclose the whole length of the chains in masonry. The temperature of the iron is thus preserved more uniform. The chains end at the level of the coping, where they connect with the cables, which are also enclosed in grout and masonry for a length of 12 feet, the latter terminating in ornamental blocks above the coping, The strength of wire is not affected by sudden changes of temperature; no further protection of the cables therefore is required.

I will add here that the anchor plates were cast of a very strong cold blast charcoal metal, at the foundry of Oliver T. Macklern, Esq., at Chippewa, who supplied the castings for the whole work.