THE BRIDGEPORT BRIDGE.

This bridge is over the western branch of the Ohio, which at Wheeling is divided by Wheeling (formerly Zane's) Island. It belongs to the same company as the suspension bridge, and was built under the same law of the State of Virginia and legalized by the same act of Congress. It is one of the common kind of wooden bridges, being a long truss strengthened by arches; it is in bad condition and needs rebuilding. This bridge is 638 feet in length and consists of three spans of about 212 feet each. Each span is composed of three trusses, with two roadways 10 feet in the clear between them, and two balcony sidewalks, 5 feet wide on the outside.

The channel on the west of Wheeling Island is no longer used for navigation. In order to improve the draught of water on Wheeling Bar, the western channel has been closed by a 6-foot dam just below the mouth of Indian Wheeling Creek. Under these circumstances it was unnecessary to make any current observations or to examine this bridge in detail.

The bridge is 53 feet above low water and 94 feet above highest water. Rafts and flats can at all times pass under, and no passage-way is required for steamboats.

Under these circumstances we have no changes to recommend in this bridge. Its original cost was $68,500.

BELLAIRE RAILROAD BRIDGE.

This is a single-track railway bridge and is being built by the Balti more and Ohio Railroad Company under the general authority given by the act of July 14, 1862. It crosses the Ohio four miles below Wheeling, and connects the main stem of the Baltimore and Ohio Railroad with the Central Ohio. The bridge is a "high" bridge 4,0013 feet long, and that portion over the river consists of six spans of the following dimensions, beginning on the Ohio side, viz, 210, 2414, 348, 213, 212, and 211 feet, so that the bridge proper has a length of 1,435 feet. These dimensions are from center to center of piers, and are in excess of the clear water-way. The trusses are of the Linville or Keystone pattern, the two longest being "through" or "over-grade" and the others "deck or under-grade." The two "through" spans are both channel-spans, giving clear openings at low water of 322 and 220 feet, respectively. It will be noted that in both the bridges built by the Baltimore and Ohio Railroad Company the span adjacent to the main-channel span (required by law to give an opening of at least 220 feet) is made a channel-span as well as the longest span. This was doubtless the intent of Congress in directing that one of the spans adjacent to the channel-span should give a 220foot opening, but the act does not require the track to be on the bottom chord, and it is not so placed in either the Steubenville or Newport and Cincinnati bridge. Moreover in this bridge the law only requires a clear opening of 300 feet, while the company has voluntarily given 22 feet more. The bottom chords of the channel-spans are 913 feet above low water, but the track being supported on roadway bearers suspended below the bottom chords, the lowest line of the channel-spans is 90 feet above low water and 40 feet above highest water. There is no daily record of the stage of water kept in Bellaire, but levelings from the highest known water-marks make the maximum oscillation of the river surface 50 feet. The two main channel-piers Nos. 3 and 4 are each 91 feet above low water; No. 2, the Ohio pier of the 220-foot channel, is 90

feet above, and the others are lower, conforming to the grades of the bridge. The foundation of pier No. 2 was laid by means of a cofferdam, but the other river-piers were commenced in caissons, the bed of the river having first been dredged to the required depth. All of the piers in the river rest on grillages composed of three thicknesses of 12 by 12 oak timber; the grillages of the main-channel piers (3 and 4) are 78 by 28; of the others, 76 by 26. The top of the foundations of Nos. 3, 4, and 5 are 15 feet below low water, and of No. 2, 9 feet below, and of No. 6, 5 feet below. The depths at which these foundations have been placed contrast very favorably with the shallow foundations of the Steubenville and the Newport and Cincinnati bridges. There is no riprap at the low-water line about either of the main-channel piers.

The line of current approaching the channel-span from above, as indicated by 6-foot floats, makes, with the piers, an angle of 40; it makes, with the perpendicular to the line of the bridge, an angle of 830, but the piers themselves, in order to conform to the line of the current, are set askew, and the trusses rest on two courses of stone, placed at an angle of 440 with the piers, but at right angles to the axis of the bridge. By this arrangement the rights of navigation are preserved, without injury to the shape of the superstructure. It is believed, from the shape of the river above, that at higher stages the current will become exactly parallel to the bridge-piers, and we therefore conclude that the company has complied with the law, that the piers shall be parallel with the current. This point could only be determined positively by waiting for high water, but the time at our disposal did not permit such a delay; and as all our information tended to corroborate the statement given above, and as the details of the piers showed a manifest intention on the part of the company to comply with the law, we did not deem it necessary to investigate the matter further. The position chosen for the bridge is on a straight section of the river, where no great changes of current can occur.

The contraction of the channel-way due to a current making an angle of 840 with the axis of the bridge is 8 feet; and, therefore, at the observed stage, (8 feet by the Wheeling marks,) the practicable opening at this bridge is 313 feet, or 13 feet more than required by the law. At most stages the reduction would probably be much less. We could make no observations on the current through the minor-channel span, as at the time of the survey this span was filled with scaffolding for the truss which was in process of erection, and a boom above deflected all floating bodies. The direction of the current through this space is probably the same as that through the principal channel opening.

The main-channel piers are 76 by 26 at the bottom where they rest upon the grillage, and are built up square to the low-water line; here there is an offset all around of 15 inches, and the piers are again carried up square to 4 feet above low water. At this elevation their dimensions are 754 by 23. Above this the sides have the batter of one-half inch to the foot, the top of the piers terminating 5 feet below the bridge-seat with the dimensions of 41 by 16 feet.

The trusses rest upon a square prism of masonry 5 feet high, 26 by 14, placed at right angles to the axis of the bridge, and therefore making an angle of 440 with the axis of the pier. The ice-breaker is a part of this pier, and commences 4 feet above low water, with a slope of 1 on 1, and terminates 29 feet above; it is built with steps of 2 feet rise and the same tread. These steps are to be filled with iron-angle blocks. Above the ice-breaker the up-stream end has a batter of one-half inch to the foot; the down-stream end has the same batter, commencing 42

feet above low water. In horizontal section, both up and down stream ends are circular. The other piers in the river are similar to the mainchannel piers, but they are somewhat smaller. The masonry, 74 by 24 at bottom, is 70 by 21 at the point where the batter commences, and 33 by 12 on top.

The grades and curvature on the bridge and approaches are as follows, commencing on the Ohio side:

The approaches on the Ohio side consist of 43 semicircular stone arches, 33 feet from center to center, (the entire length being 1,490 feet,) and two spans of Bollman deck-bridge, 105 and 107 feet long, respectively. This approach is very massive and imposing, and reflects great credit upon the company, being as safe and as durable as a track on solid ground, and permitting any rate of speed with safety. The piers of the arches are 103 by 53, the clear span of each arch being 28 feet. The arcade is 12 feet wide on top, being designed for a single track. The piers of the arcade are all founded on three feet of concrete, laid at various depths, from 8 to 26 feet below the natural surface. The two shore-piers between the end of the arcade and the bridge proper are 22 by 10 on top, also resting on three feet of concrete, placed at depths of 20 and 6 feet, respectively, above low water.

The approaches on the Benwood, or Virginia, side consist of eight Bollman deck-trusses, each with a span of 108 feet, making a total length of 864 feet. The piers for these trusses have the same general dimensions as the shore-piers on the Ohio side, and their foundations are from 10 to 30 feet below the natural surface. The arcade on the Ohio side was nearly finished at the time of our inspection, but very little had been done on the Virginia side. The bridge will probably be finished during the coming summer.

At the time of the surveys the water stood at 8.5 by the marks at Wheeling. At this time the section of the river at a point 800 feet above the bridge was 11,105 square feet, and the discharge was 36,261 cubic feet per second, showing an average velocity of 3.265 per second or 2,226 miles per hour. The floats through the channel-span had a velocity of 3.1 miles per hour. The actual water-way on the line of the bridge at the date of the survey was 10,532 square feet, which being 5 per cent. less than the natural section above, showed that the average velocity of the water must be increased 5 per cent. on account of the space occupied by the piers. The total high-water section at the bridge-site is 74,787 square feet, of which 6,735 square feet, or 9 per cent., is occupied by the bridge-piers, and this would probably cause an increase in the mean velocity at that stage of the same amount. The low-water section is 3,425 square feet, of which 506 square feet, or 15 per cent., is obstructed. This, however, would make no material difference, as the bridge is built in a pool. No regular record of the rise and fall of the river having been kept at this locality, the duration of the various stages can only be ascertained approximately by an examination of the record at Wheeling, which is only four miles above. It should be kept in mind, however, that the maximum oscillation at Bellaire is reported at 50 feet, while at Wheeling it is 434.

The losses at this bridge up to date, as given in the statement of John F. Dravo, president of the Coal Exchange, (Appendix B,) amount to $60,500. Some of these were due to causes connected with the process of construction that will not be permanent.

The greatest objection to the location of this bridge is the proximity of extensive rolling-mills on both sides of the river. The smoke from these mills frequently lies so low that navigation even without a bridge is made difficult. This is a cause, however, that admits of no remedy unless a law should be made to compel factories to consume their smoke, of which there seems no present likelihood. The accident to the towboat Star, referred to in connection with the Steubenville bridge, is an illustration of the incidental dangers of navigating the Upper Ohio. The board have not only no changes to recommend in this bridge, but they feel called upon to commend both the excellent manner in which it is constructed and the liberality with which the company has secured to navigation, at considerably extra expense, more than they were required by law to give. We have not been able to ascertain what will be the cost of this bridge when finished; but it will probably be the most expensive work of the kind on the river. The money, however, will have been wisely expended.

PARKERSBURGH BRIDGE.

This is a single-track railway bridge, belonging to the Baltimore and Ohio Railroad Company, and it is designed to connect their Parkersburgh branch with the Marietta and Cincinnati Railroad. It has just been finished, having been opened to travel in February last. It has been constructed under the general authority to build bridges above the mouth of the Big Sandy which is given by the act of July 14, 1862, (Appendix A,) under which the Steubenville and Bellaire bridges are built. It is a "high" bridge, with a total length between abutments of 4,262 feet. That portion over the river consists of six spans of the following dimensions, commenced from the north or Belpre side, viz, 210, 350, 350, 210, 210, 210, making a total length over the river proper of 1,540 feet. These dimensions are from center to center of piers, and must be reduced by the widths of the piers to get the clear water-way. These trusses are of the Linville or Keystone pattern, the two longest being "through" or "over-grade" bridges, and the other "deck" or "undergrade." The two high spans are both channel-spans, and give clear openings at low water, measured on the axis of the bridge, of 326 feet. The bottom chords of the channel-spans are 91 feet above low water, but the track being supported by road-way bearers suspended below the bottom chords as in the Bellaire bridge, the lowest line of the channel-spans is 90 feet above low water, and forty feet above highest water. There is no daily record kept here of the stages of the river, but the greatest known oscillation is reported to be 50 feet. The tops of all the piers in the river, excepting the first one on the Ohio side, are 91 feet above low water; the latter is somewhat lower, conforming to the grade of the bridge. The foundations of piers 1 and 7 are 3 feet below low water; of 2, 3, 4, and 5, 20 feet below; and that of No. 6, 18 feet below. No. 1 has its foundation 16 feet below the natural surface; No. 2, 21 feet; No. 3, 12 feet; No. 4, 9 feet; No. 5, 15 feet; No. 6, 20 feet; and No. 7, 40 feet. All of these piers are built upon grillages composed of three courses of 12 by 12 white-oak timber, projecting on all sides two feet beyond the masonry. Piers 2 and 6 are reported to rest on the rock. The foundations of all the river-piers were put in place by means of

coffer-dams, the lower portions of which were made solid with 12 by 12 timbers up to 5 feet below the low water line. This part of the work was begun in May, 1869, and completed before the close of the season. There will be no riprap at the low-water line about any of the riverpiers. Their foundations are laid so deep that but little protection will be necessary, and what is used will be below low water, and thus the entire channel-way will be available for navigation.

This bridge being located in a bend, the currents are naturally curved, varying somewhat with the different stages of the river. No floats could be sent through the northern channel-span, as at the time of observations it was obstructed by a boom and trestle-work. Under these circumstances the most accurate method of determining the angle between the piers and the current was to find the normal to the curves of the current, and then the angle between this normal and the line of the bridge. The angle thus determined was found to be 5° 30", and this, therefore, is the angle between the axis of the piers and the line of the current. The contraction of the available width by this obliquity is 83 feet, thus leaving two practicable channel-ways of 318 feet each. As the law only required one channel-space of 300 feet, the bridge campany are deserving of very great credit in not only providing two channelspans instead of one, but in making each 18 feet wider than required by law for the widest. We are credibly informed that it was the original intention of the company to have built this bridge exactly like that at Bellaire, but after they had started the piers of their main-channel span a protest was made against this span by the coal-boat interest. The latter claimed that although the main span was over the deepest water of the river, it was yet not over the coal-boat channel, as the very abrupt bend in the Ohio, just below the bridge, made it necessary for coal-tows to hug the Ohio shore, that they might not drift on to the Virginia shore after passing the bridge. An estimate was made of the cost of making an additional channel-span near the Ohio shore, and it was found that it would increase the cost of the bridge by $60,000.

The railroad company very liberally offered to bear half of this addi tional expense, provided the coal-men furnished the other half. The latter decided that unless they obtained a new channel-span, they might in a single year lose more by collision, or by running ashore, than the sum required, and therefore the money was advanced at once. A full statement of the amount paid by each subscriber is given in Appendix C, certified to by the president of the Coal Exchange. This is one of those special cases showing how important it is that the positions of bridge-piers should be carefully decided upon by some disinterested authority before they are commenced. The whole course of the railroad company forbids the supposition that they designed unnecessarily embarrassing navigation, and yet a serious obstruction would have been caused but for the expenditure of a large sum by the principal tow-boat

owners.

Piers 2, 3, and 4 are 82 by 28 feet at bottom, where they rest on the timber foundations. They are carried up to low-water line with vertical offsets, and at that elevation they measure 75 by 24 feet. From low water the sides are carried up to the bridge seat with the batter of onehalf inch to the foot. On the up-stream ends the ice-breakers are formed like those at Bellaire, with two-foot offsets on a slope of 45° to the height of 26 feet. Above them the up-stream end is built up with the same batter as the sides, to within 4 feet of the top, where there are two two-foot offsets. The down-stream ends have the usual batter, with similar offsets at top. The dimensions of the channel-piers on top are