Suspension Bridge over the Missouri River. - To Kansas City belongs the honor of building the pioneer bridge over the Missouri. On the south or west side of the river the Pacific Railroad (of Missouri) extends from St. Louis to the State line at Kansas City; the Kansas Pacific Railway, late Union Pacific Eastern Division, is now in operation 405 miles west from the same point of the boundary. The Missouri River Railroad, now operated in connection with the Missouri Pacific, continues that line up the river to Leavenworth; and the Missouri River, Fort Scott, and Gulf Railroad, running at present to Paola, 40 miles south, is being pushed rapidly to the Indian Territory, and will become the great route from the North to the South-west. On the opposite river bank the North Missouri Railroad forms a second line to St. Louis; the Missouri Valley Railroad runs northward to St. Joseph; and the Kansas City and Cameron Railroad, forming part of the Hannibal and St. Joseph Railroad line, opens a direct route to Chicago. The bridge, now completed, was built by the last-named road, and will enable the seven roads to unite at common points within the city.

The location of the bridge is opposite the town, and immediately below a bend in the river. It was begun in January, 1867. In February, Mr. Chanute, the chief engineer, took charge of the works. In the spring the enterprise was interrupted by a high flood, and it was not until August that work could be resumed. The south abutment of the bridge was placed 80 feet back from the face of the bluff, and from it a 66-foot span extends over a street and the track of the Missouri Pacific Railroad to a pair of pillars standing near the edge of the rock face; a span of 133 feet reaches from them to pier No. 1, the first river pier. A pivotdraw of two spans, each 160 feet in the clear, and 363 feet long over all, from centre to centre of piers Nos. 1 and 3, turns upon pier No. 2, which is placed as nearly as possible in the centre of the channel. Pier No. 4 was located 250 feet beyond No. 3; No. 5, 200 feet further north, on the edge of the sand-bar; and two spans, 200 and 177 feet respectively, cover the distance remaining to pier No. 7, which stands on the edge of the wooded shore, taking the place of a north abutment. The railroad is then carried over the bottom land on 2,360 feet of trestle-work, descending one foot in 100 to an embankment. The carriageway is carried down on a heavier grade by a side trestle.

The difficulties attending the building of this bridge were wholly in the foundations. The length of the structure is one mile.

The masonry of all the piers is of limestone, quarried in the neighborhood, the facing being of ashlar, and the backing of heavy rubble. The ashlar of the upper courses, above the icebreaker, is of a good blue-stone, of uniform color, and the stones used below are of a grayish tint. The piers finish 11 feet higher than the great flood of 1844, and 48 feet above the lowest water observed. The total height of pier No. 4, from rock to coping, is 89 feet. The pivot pier is circular in form, and 29 feet in diameter, finishing 32 feet on top.

The entire structure was completed by July 3, 1869.

The Mississippi Bridge at St. Louis.-Work on the Mississippi bridge at St. Louis is rapidly being pushed forward. The shore pier on the St. Louis side has been completed to a point above low-water mark, and the dredge-boats are now employed in sinking a caisson for the second pier, which will be located about 300 or 400 feet from the shore. The bed rock has been sounded. In order to hasten the completion of the bridge, a large body of workmen is engaged on the Illinois side, digging for the final completion of the pier, and within two or three weeks the second pier in the water and the fourth pier on the Illinois side will be under way. The most difficult pier to construct is the third, near the centre of the stream, owing to the rapidity of the current, and the sloping character of the rock's bed. Engineering skill will, however, overcome all these obstacles, and so soon as the second pier is under way, the caisson will be sunk for the central one. The levee for several squares is covered with stone, brick and lumber, which are being prepared for their respective positions. The estimated final cost of the structure is 7,000,000 dollars, 4,000,000 dollars of which have already been raised. As the work progresses, the legislature, city council, and the county court will undoubtedly send sufficient aid to complete the work at an early day. The rapid currents, quicksands, and other difficulties incidental to spanning a great stream like the Mississippi, will necessarily prolong the work, but that within three years, at the farthest, the bridge will be duly inaugurated, there can be but little doubt. Captain Eads is laboring with great energy; he is the chief engineer. While in Europe he visited all the bridges of note, and secured translations of the various reports of civil engineers on the subject of bridgebuilding, with a view of employing in the construction of the bridge the most approved plans, so as to secure a work that will be not only a model of beauty, but durable as well. Associated with him is Henry Fladd, a man who ranks deservedly high among practical and scientific engineers. Both are confident of completing the bridge in three years at the longest, and even talk of two years as the most probable time. The work of tunnelling Washington Avenue, St. Louis, will not prove as difficult a task as many suppose, and it is believed that it can be accomplished without disturbing even the sewer-water or gas-mains. Should this operation prove too hazardous, then an elevated railway will be constructed. In either event the road will terminate in a grand union depot near Fourteenth Street, forming a direct communication with the Pacific and other roads. St. Louis Times.

The Dusseldorf Bridge. The great railway bridge over the Rhine, near the village of Hamm, a little above Dusseldorf, is progressing rapidly, and will probably be completed before the end of November. The bridge is to consist of 4 arches, the upper part of which will be made of iron. The iron work of each arch will weigh 14,000 centners. The bridge is united to the main line on the left bank by a viaduct, consisting of 15 stone arches, but this viaduct does not immediately join the bridge; it

is separated from it by a revolving drawbridge, so that the line can be rendered impassable at any moment. On the right bank a fort is being built, which will command the bridge.

Bridge at Omaha, U. S.-One of the most important works on the Union Pacific Railroad-the construction of a bridge across the Missouri River, at Omaha, 400 miles west of Chicago-is about to be commenced by General G. M. Dodge, engineer of the Union Pacific Railway. The bridge is about 2,800 feet long, and is divided into 11 spans of 250 feet each, the piers being cylinders of cast iron, 8 feet 6 inches in diameter, and filled with concrete. The treacherous bottom of the Missouri River presents more than ordinary difficulties in obtaining a reliable foundation, from the great depth of the shifting sand, which is constantly filling up old channels, and opening fresh ones, so that the section of the bed is ever varying. Where it is possible, the cylinders will be lowered on to the rock, and elsewhere, to a depth of 70 feet below low water, in the sand, the bases being enlarged from 8 feet 6 inches to 12 feet in diameter, to spread the bearing surface, which will also be increased by flat bars projecting from the foot of the cylinder into the surrounding sand. Foundations of this class have been successfully employed by the Hon. W. J. McAlpine, in various bridges he has constructed. The length of the cylinders, from low water to the underside of the girders, will be 69 feet, making a total height of the main columns of 139 feet. The 10 piers, each with two cylinders, will be braced transversely, and protected up stream with ice-breakers attached to columns 5 feet diameter, and placed 20 feet in advance of the piers. The faces will be of cast-iron plates, meeting at an angle of 45 degrees, in front of the columns to which they are braced with oak timber, the intermediate spaces being filled with rubble and concrete. From below low water to the highest flood levels, the cylinders will be cased by plates, and the enclosed space will be enclosed with concrete, to prevent any accumulation of ice, or other obstructions, which may be carried down the stream, from getting between the cylinders, and straining them on the intermediate bracing. The girders of the superstructure will be trusses made of wrought iron, with the exception of a cast upper chord. The approaches to the bridge on both shores will be on a gradient of one in 30, made in embankment on the eastern side to a height of 40 feet above the ground, the remainder being a viaduct of trestlework. The total length of the whole, including the river crossing, will be about 3 miles.-Journal of the Franklin Institute, March, 1869.

Concrete Bridge. The tests applied to the experimental bridge of concrete, set in cement, erected over that branch of the Metropolitan District Railway which forms one of the junctions between the circular line and the West London Extension, prove conclusively the reliable character of concrete exposed to compressive strains. The structure experimented upon spans the open cutting between Gloucester-Road Station and Earle's Court Road. It is a flat arch of 75 feet span, and 7 feet 6 inches rise in the centre, where the concrete is 3 feet 6 inches in thickness, increasing towards the

haunches, which abut upon the concrete skewbacks. The material of which the bridge is made is formed of gravel and Portland cement, blended in the proportions of six to one, carefully laid in mass upon close boarding set upon the centring, and enclosed at the sides. In testing the bridge, rails were laid upon sleepers over the arch, which brought a load of two seventy-fifths of a ton per foot run upon the structure. Seven trucks, weighing, together with their loads, 49 tons, were formed into a train, having a wheelbase of 57 feet; hence the rolling load amounted to forty-ninefifty-sevenths of a ton per foot run. The deflection produced by the passage to and fro of this train four times was noted upon a standard, cemented to the side of the arch, at a distance of onethird the span from the abutments. When one side of the bridge was loaded, the extreme rise of the branch on the opposite side was about one-sixteenth of an inch, which was produced by a maximum strain of 10 tons 14 cwt. per square foot. At a subsequent trial, a mass of gravel, 10 feet wide and 3 feet thick at the crown, and 6 feet deep at the haunches, was laid over the bridge, and upon this, ballast was placed the permanent way. After an interval of a few days, the trucks, loaded as before, were passed over the bridge, at first in pairs, and finally all together. In this test the strain upon the concrete was as follows:

7 tons 17 cwt.

4 tons 8 cwt.

12 tons 5 cwt.

2 tons 17 cwt.

15 tons 2 owt.

After repeated transit, the load was left upon the bridge all night, and the arch, upon examination, showed no signs of failure or distress under the severe strains to which it had been exposed. From these trials it is fair to assume, that a thoroughly well-constructed arch of concrete is absolutely stronger than a similar one of brick; but in practice the danger arises that it would be difficult to ensure so high a quality of concrete as that employed in the present instance, and the proper supervision of the contractor's work by the engineer would be almost impossible in structures of this material, whilst the inspection of brick-work is an easy matter. The utter uselessness of inferior concrete was shown by the failure of the bridge which was previously erected on the site of the present one, which yielded under its own load when the centres were struck.

Blackfriars New Bridge.-Blackfriars bridge is altogether formed of wrought iron, so far as the main structure is concerned, the embellishment only being of cast metal. Preparatory to the actual commencement of this important undertaking, the erection of a temporary wooden substitute, as well as the demolition of the old bridge, was necessary. The first piles, for the requisite gantry, -one-third of which is now removed, - were driven in June, 1864. As it is generally considered in the London district that the London clay must be reached to obtain a sure foundation for large

buildings, this course was here followed, involving 3 or 4 months of incessant daily and nightly anxiety and labor, on account of the tides. For our part, however, we coincide with the opinion of some eminent practical engineers, that there is no absolute necessity for going to this clay, and that, consequently, in doing so, much needless expenditure of time and money is incurred. The bridge consists of 5 arches, namely, two of 155 feet span each, two of 175 feet, and one of 185 feet. The height of rise in the centre arch is 17 feet, and in the others 16 feet and 12 feet respectively. Instead of regularly framed centring, piles were driven down to support the ribs where required, which doubtless saved the contractor much expense both in erection and demolition. The ribs were then wedged up to the soffit of the arch; these wedges or slacks are now removed, so that each arch rests on its own skewbacks, and the piles can be taken away at once. Mallet's patent buckled plates, which, as most of our readers know, are made of about one-quarter inch plates of iron placed heated over a mould, and stamped by hydraulic pressure into the shape of a groined arch, are bolted to the roadway bearers by five-eighths inch rivets, and form an immensely strong platform. On this is put one inch thick of asphalte; over this again-an addition to and improvement on the usual practice. -a layer of broken stones and asphalte, from 9 inches to 12 inches in thickness, is placed; and lastly, on top of all, is granite-pitching as ordinarily laid on roads. The total length of the bridge is 1,272 feet; its width, including the roadway of 45 feet, and two footpaths of 15 feet each, is 75 feet. The gradient is one in 40. There are 8 polished red granite columns, between which there are parapets 3 feet 9 inches in height. Over each column there are recesses in which there are seats capable of resting ten or a dozen weary pedestrians. A handsome row of lamps will be placed along each pathway, a little back from the curb, — a plan not adopted on any other of the Thames bridges,—and they will be so arranged as to facilitate the navigator after dark.. The balustrades are Venetian-Gothic in design.- Van Nostrand's Eng. Mag., Sept.,

1869.

The Cincinnati and Newport Bridge. All preliminary arrangements and work have now been begun upon this bridge, which is to connect Butler Street, in Cincinnati, with Saratoga Street, in Newport, Kentucky. The stone-work of all the piers is to be of the best limestone, up to the line of high water, and freestone above that, excepting the two piers of the middle, or long span, which will be entirely limestone. Much of the stone for the piers has already been quarried. George A. Smith, of Cincinnati, has the contract for the stone-work. The bridge proper will be of the best wrought iron, in lower and upper chords, uprights, braces, etc. No timber will be used save in the flooring. The train, as seen, will be about 100 feet above low water. This span is planned at a length of 420 feet; the one next south is 240 feet, and the others as near 200 feet each as the division of distance will admit. There will be 7 spans in all, with the 8 piers.

yond the front streets of both Newport and Cincinnati, the