At present the engineers are progressing with the work of placing large hydraulic jacks in the tops of the piers and abutments preparatory to finishing the work. These will be of immense power, each calculated to raise thousands of tons. They will be used—so soon as the weather moderates—to raise strongly built wood- en towers upon which the chains that support the arch cords are to rest while being put together. These chains are perfect curiosities in their way, and for strength and size are far superior to anything of the kind ever heard of. The links are composed of 1/8 inch iron, 6 inches wide and 3 feet long. There will be five stands of these to each chain, which will be made of sufficient length to admit of their being extended over the wooden towers referred to, and about 100 feet on each side. The idea is to use them for a purpose similar to that for which hog-chains are employed in the construction of boats, the great difference being that they can stand a tension equal to the hog-chains of all the steamers on the Mississippi. The arch cords referred to will be composed of staved tubes beeped like barrels, made of steel and in 12-foot lengths. There will be 1,012 of these, 900 of which have been completed, and as the Keystone Bridge Company is manufacturing at the rate of 200 per month, this, the most important and largest part of the superstructure, will be completed in a few weeks. These tubes are perfectly straight, the arching being accomplished by turning a very slight bow in the side ends. They will fit together perfectly, and at the junctions will be secured by strong cast-steel hammered clamps, with slats cut in the inside to correspond with a series of turned collars on the tubes. The two parts of the clamp will be drawn together, and the collar squeezed home by means of a large steel key and temporary appliances to each, running through corresponding orifices made in both. To these pins a hammered charcoal iron bar, 12 inches wide and 1 inch thick, will be fastened on each side, and thus connect the upper and lower pipe-cords, which are 12 feet apart. Such is the perfection with which this work was calculated and done, that were either the bevelling of the tubes or the turning of the slats and collars but a thousandth part of an inch wrong it would throw the arch several inches out of place only 12 feet from the defective point. Indeed, the entire cord will, when finished, be as precise as the machinery of a clock. There is every reason to believe that everything connected with it will move along smoothly when work is assumed in force, and that by the first day of July locomotives will be merrily whistling down brakes “s they come near the East S. Louis approach preparatory to crossing. In anticipation of this much wished-for event, it is proposed to let the contract for the erection of the East St. Louis approach immediately, and as the structure will be composed entirely of trestle and iron, competent engineers state that three months will be ample time to complete it.