The approach to this bridge on the Indiana shore consists of a long and high embankment. This, however, does not properly belong to the bridge, and, in accordance with the rule adopted for other bridges, we consider that we have reached the end of a bridge when we come to earth-work. Under this rule, this bridge has no approaches, the entire space from abutment to abutment being water-way.

This bridge crosses the Louisville and Portland Canal 1,700 feet below the guard-lock at the head. An unobstructed passage-way for steamboats is secured by means of a draw, giving a clear opening of 114 feet over the canal. The other end of the draw projects over a portion of the river, and by modifying the canal bank on this side so that it shall just have the width of the pivot of the draw, it will be practicable for steamboats in high water to ascend the river without lowering their chimneys. This is a very valuable provision for boats that habitually run where there are no bridges, which yet may occasionally wish to go above Louisville. In low water such boats can pass through the canal, and in high water, by using the other end of the same draw, they can pass up the river, even should they be too wide to get through the new locks. The changes in the canal bank necessary to permit this use of the northern end of the draw are being made by the United States as a necessary adjunct to the enlargement of the canal.

The total high-water section of the river, on the line of the bridge, is 216,249 square feet, of which 13,573 square feet, or 6 per cent., is occupied by the piers. This contraction would probably cause no perceptible increase of velocity. The low-water section is 1,377 square feet, of which 60 square feet, or 4 per cent., is obstructed. All the water at this stage is running through the Indiana chute, but there being no navigation possible, the effect of the piers need not be considered.

The losses by collision with the piers of this bridge, up to date, amount to $26,704. (Appendix B.)

The board have no changes to recommend in this bridge, which they consider a first-class structure throughout, and very much less an obstruction than it might have been had its builders limited themselves to giving only what they were compelled by law to give. On the contrary, they have chosen to build according to the highest of the three authorized plans, and have exceeded the heights and widths that even this plan required, spending $150,000 more than was necessary to comply with the letter of the law. Instead of a 300-foot opening at low water, one of their channel-spans gives 380 feet, and the other 352 feet. The total cost of the bridge, from abutment to abutment, was $1,615,120.

If it should be found by experience that, owing to the peculiar location of this bridge, the channel-space on the Indiana side cannot be safely run by coal-tows, then a still wider opening will be necessary. Present difficulties, however, may possibly be due to a lack of experience. Should it be found, however, that there are inevitable dangers due to this exceptional location which no amount of experience can avoid, it will be manifestly necessary to widen this span to 500 feet, or in some manner to modify existing conditions, so as to facilitate the passage of the present opening.

The record of the average and the extreme stages of the river for the years 1851, 1858, 1859, 1866, 1867, 1868, 1869, and 1870, is given in the following tables for the head and the foot of the falls. No other records of the stage of water on the falls could be obtained. As the main channel opening of the bridge is located below the head and above the foot of the falls, the exact space under the bridge cannot be obtained from these tables, and has, therefore, been omitted. At the head of the

falls the heights above low water are also the available depths for navigation, as during extreme low water the rocks in the channel are bare. River record at head of falls-average duration of each stage.

The marked discrepancy between the oscillations at the head and at the foot of the falls is due to the tendency of all rivers, when in flood, to obliterate all irregularities in their beds, and to establish a regular surface slope. During low stages the rise below the falls is three feet for one foot above. This ratio gradually decreases as the river rises. until a depth of 18 feet is attained at the head of the falls, after which the rise is the same above that it is below.

THE PADUCAH BRIDGE.

The authority to construct a bridge at Paducah was granted by the joint resolution of Congress approved April 7, 1869, (Appendix A.) which is supplementary to the act of July 14, 1862. The authority is exactly the same as that for constructing the Newport and Cincinnati bridge, and if the company so elect, it will permit the construction of a similar bridge to that which Congress has just ordered to be raised. In our report of February 7, 1871, which has been printed as Executive Document No. 128, of the third session of the Forty-first Congress, we recommended that the joint resolution of April 7, 1869, be repealed. and that a general act be passed to regulate the construction of all future bridges over the Ohio, a copy of which is embodied in this report. (See Appendix E.) If built under this act it is believed that the bridge at Paducah will not be injurious to navigation. As no steps have yet been taken toward building this bridge, the law can now be readily changed.

There are no regular observations kept at Paducah of the rise and fall of the river, but the maximum oscillation is reported as 521 feet. As the duration of high stages is much longer in this portion of the river than it is above, there is a much greater necessity for a high bridge. The river slope in the Lower Ohio is much more gentle than it is above the falls. From Pittsburg to Beaver Shoals the fall averages 14 inches per mile, while from Portland to Cairo it is only 24 inches per mile. This reduced fall makes a more gentle current, and as the river is quite straight above and below the bridge site, there ought to be no difficulty in passing through a 400-foot channel space. It should be remarked, however, that as the proposed bridge is below the mouths of the Cumberland and the Tennessee, there will probably be a greater number of boats to pass this bridge. A low drawbridge at this locality would be an even greater obstruction than at Cincinnati, and, therefore, the law authorizing one should be repealed.

The average duration of different stages of water, as reported by Mr. Harrington, the city engineer of Paducah, is as follows:

Between low water and 10 feet

Between 10 and 20 feet

Between 20 and 30 feet.

Between 30 and 40 feet..
Between 40 and above.

6 months.

24 month. 13 months.

5 weeks. 3 weeks.

12 months.

The duration of high stages is quite variable, however. The river averages 40 feet and over, twice in every three years, though there have been periods of four successive years in which it did not rise so high, and then again in the four following years it was over 40 feet each year, and in one year it exceeded this height four times. The highest

water ever known was in 1867, which exceeded all previous floods by three feet.

No definite location having been given to this bridge, we did not deem it necessary to take our surveying party to make current observations. A map accompanies this report, showing the locality and the soundings, as made by the bridge engineers in their preliminary surveys. On these soundings the low-water section is 33,400 square feet, and the highwater section is about 257,600 square feet.

CONCLUSION.

The following tabular statement of the principal features of the bridges over the Ohio, together with the cost of each bridge as far as ascertained, is appended. Nothing but the actual cost between abutments has been taken, all land damages and connections with the main branch having been excluded.

NOTE. The lengths of earthen embankments are not included in the above.

The following maps and drawings accompany this report: Railroad bridge at Steubenville; highway bridges at Wheeling and Bridgeport; railroad bridge at Bellaire; railroad bridge at Parkersburg; railroad and highway bridge at Newport, highway bridge at Covington, on one sheet; railroad bridge at Louisville; site of proposed railway bridge at Paducah. Each sheet shows the plan of the bridge and a map of the river for at least half a mile above and the same distance below, on the scale of 1 inch to 200 feet, with all current observations accurately platted thereon. The profile of each bridge and two elevations of a channel-pier are given on a scale of 1 inch to 20 feet. Each sheet also contains small map, on a scale of 2 inches to the mile, showing the bends in the river for about five miles above and the same distance below. The Paducah sheet is like the others, excepting that no bridge is represented.

Appendix A contains the United States laws appointing the Board of Engineers, and those authorizing the construction of the various bridges. Appendix B contains a statement of the losses sustained by collision