same safe for public use, and so as not to hinder the general use of said bridge for ordinary travel, which shall be ascertained by one or more experienced civil engineers, who shall report, by proper surveys and estimates, to the Secretary of the Interior for his approval; the whole cost of which survey and construction of said additional bridge for the purposes aforesaid to be paid by the said company. And the said company shall construct such draws as shall correspond with those now in use on the said bridge, and of such model as shall be determined by the Secretary of the Interior, and which shall afford reasonable facilities for navigation on the Potomac River."

32. "An act making appropriations for sundry civil expenses of the government for the year ending the 30th of June, 1862, and for other purposes," approved July 2, 1864.-(Vol. 13, page 344.)

For repairs of Potomac and Upper bridges, $6,000; for repairs of Navy Yard bridge, $25,000; for repairs of Little Falls bridge, $250.

33. "An act making appropriations for sundry civil expenses of the government for the year ending June 30, 1866, and additional appropriations for the current fiscal year," approved March 3, 1865.-(Vol. 13, page 445.)

For repairs of the Navy Yard bridge, to enable the Commissioner of Public Buildings to erect a new draw, $1,000.

34. "An act making additional appropriations, and to supply the deficiency in the appropriations for sundry civil expenses of the government." (Vol. 14, page 14.)

For repairs of the Potomac and Upper bridges, $6,000.

35. "An act making appropriations for sundry civil expenses of the government for the year ending June 30, 1867, and for other purposes," approved July 28, 1866.-(Vol. 14, page 310.)

To enable the Commissioner of Public Buildings to put in thorough repair the bridge across the Potomac at Little Falls, in accordance with the estimates of the engineer, $2,410. For casual repairs of the Potomac Navy Yard, and Upper bridges, $6,000. For erecting a new draw in Navy Yard bridge, $5,000.

36. "Joint resolution making an appropriation for the repairs of the Potomac bridge," approved June 18, 1866.-(Vol. 14, page 360.)

That the sum of $10,000 be and the same is hereby appropriated to enable the Commissioner of Public Buildings to place the Potomac bridge in such repair as to render it permanently passable, the work to be done immediately after the approval of this joint resolution.

37. "An act making appropriations for sundry civil expenses of the government for the year ending June 30, 1868, and for other purposes," approved March 2, 1867.-(Vol. 14, page 457.)

For casual repairs of the Navy Yard and Upper bridges, $6,000.

38. "An act making appropriations to supply deficiencies in the appropriations for the service of the government for the fiscal year ending June 30, 1867, and for other purposes," approved March 2, 1867.-(Vol. 14, page 468.)

To pay deficiencies and keep in repair the bridge at or near the Little Falls, Potomac River, $3,350.

39. "An act making appropriations to supply deficiencies in the ap propriations for contingent expenses of the Senate of the United States for the fiscal year ending June 30, 1867, and for other purposes," approved March 29, 1867.

For the repairs of the Long bridge, District of Columbia, to be expended under the direction of the Secretary of War, $15,000.

40. "An act making appropriations for sundry civil expenses of the government for the year ending June 30, 1869," approved July 20, 1868.

For casual repairs of the Navy Yard and Upper bridges, $3,000. For repairs and taking care of the bridge, at or near the Little Falls of the Potomac River, $26,000. For repairs of the Long bridge, $15,000.

41. "An act making appropriations for sundry civil expenses of the government for the year ending June 30, 1870, and for other purposes," approved March 3, 1869.

For repairs of the Long bridge, $5,000. For casual repairs of the Navy Yard and Upper bridges, $3,000. For repairs and taking care of the bridge, at or near the Little Falls, $2,000.

It is to be regretted that but few of the reports, plans, and estimates of the different bridges are now available, and it would require very diligent search to find them among the archives of the several departments having at different times the control of the building and repair of these structures; but in their absence, several interesting facts concerning those works, aside from the various amounts appropriated and expended upon them, are furnished by the statutes just quoted. The first Potomac bridge was built in 1809 by a company on the site of the present one, and remained in uninterrupted use until 1831, when a large part was carried away by a very great freshet, and masses of floating ice. An act of 1830 makes the first appropriation and directs certain alterations to be made, consisting in lengthening the draws, planking the sides of the spaces covered by them, and that the opposite sides of the wharves above and below the bridge should be curved off in a circular form. By an act approved in 1832, and subsequently amended in 1834 and 1835, the bridge was purchased by the government of the United States, and the report of the engineer, dated December 30, 1835, states that it "has been completely finished, according to the terms of the contract, in all its points; and since the 28th of October last, has been thrown open to the general travel." The bridge was first rendered passable on the 1st of October, on which day "the President and cabinet crossed it on foot and returned in carriages. The bridge then constructed was substantially the same as that which now exists; that is, the part crossing the shoal was made a causeway and connected with the shores by wooden bridges resting on piers. For a few years the bridge escaped without damage, when, in 1840, a portion was again destroyed by ice. Without exact data it is impossible to enumerate all of the different occasions upon which it was injured; but it is known that such was the case, and very severely so, in 1856, 1860, 1863, 1866, and 1867. In several instances many spans were carried away and travel suspended for many months at a time. It is also ascertained with great certainty that, in a majority of the cases, the accidents occurred to those portions built on piles where the spans are short and low. Toward the Virginia shore, where the bridge rests on piers with a clear water-way of over one hundred feet between them, through which the floating matter, drift, and ice may freely pass, no injuries of a serious nature have been sustained, at least not from that particular cause. The railroad bridge, which is owned by the Washington, Alexandria and Georgetown Railroad Company, was built in 1863 and 1864, and is about seventy-five feet below and parallel to the Long bridge. The repairs being made to strengthen the southern section of the former, that portion between the span over the main channel and the Virginia shore, and against the plan of which the remonstrances were made and the attention of the

receiver of the road called by letter previously mentioned, are immediately below the spans of the Long Bridge, which are referred to above. The repairs consisting in driving intermediate piles between the old piers, and thus subdividing the spans into sections of from eleven to eighteen feet, will most certainly, in the opinion of any disinterested person, cause a formidable obstruction, and be the means of greatly impeding the flow of the drift and ice, which, owing to the greater width of the spans, can safely pass the upper bridge. The material brought down will become packed against these piles, partially if not completely forming a dam, and thereby closing up the space between the two bridges; the only outlet would then be by the channel way through the draws. Should the coming winter be even moderately severe, judging from past experience and natural cause and effect, the destruction of those portions of the two bridges will prove inevitable. The railroad authorities still continue the strengthening of their bridge by driving piles, when other plans might be easily substituted; previous to the commencement of the work the six spaces between the Virginia shore and the Georgetown channel were from one hundred to one hundred and twenty-five feet in length, resting on wooden piers or cribs, and were amply efficient for all purposes. The original design of the bridge is being very considerably altered, transforming the truss bridge into one on piles. The current of the river at this point becomes very rapid, and at the breaking up of the winter large bodies of ice come down with great force, while in the spring the larger portion of the drift from the upper Potomac is carried with increased velocity through the Virginia or Georgetown channel. "The great depth of this channel and the velocities of the current there during floods are sufficient causes against the erection of many piers." In some portions of the Long bridge, where piles have been driven at from twenty-two to thirty feet apart, the ice and drift accumulate above it for upward of forty and fifty feet, and so close to the structure as to bear the weight of several men. These facts alone should prove a satisfactory reason why no additional obstructions, especially when so unnecessary, and while other plans could be successfully adopted, be allowed to be placed in the bed of the river, and competent authority should compel the company to desist from further encroachments upon the channel way.

The committee on the part of the corporate authorities of the city of Georgetown have been advised that certain repairs, those previously referred to, were being made to the railroad bridge over the Potomac River, which may have the effect to impair and destroy the channel of the river so far as the port of Georgetown is concerned, and are desirous of ascertaining the probable extent of such damage and injury. In the act providing for the purchase by the United States of the rights of the Washington Bridge Company, and for the erection of a public bridge on the site thereof, and which was approved July 14, 1832, appears the clause "that in the selection of materials, and in the construction of said bridge, draws and arches, all practicable attention shall be paid to the preservation of the navigation of the said river." The law applying to the construction of the one bridge should certainly be enforced in the building or repairing of the other structure, the more especially as Congress the very following year appropriated one hundred and fifty thousand dollars "to remove obstructions by enlarging and deepening the channel,” and for other purposes; when such large expenditures are made to improve a channel, it certainly becomes those most interested that "every attention shall be had to the preservation of the navigation." The care of

this preservation by "An act to alter the bridge and draw across the Potomac from Washington to Alexander's Island, approved May 14, 1850," is given to the council. Section third of the act reads "that the council shall have power to * * to superintend the health of the city, to preserve the navigation of the Potomac and Anacostia Rivers adjoining the city; to erect, repair, and regulate wharves; to deepen the docks and basins, &c."

The law thereby also appoints the proper persons to watch over and preserve the navigation.

The question now arises whether the certain repairs being made on the railroad bridge will have the effect to destroy the channel of the river so far as the port of Georgetown is concerned. After a careful study and consideration, it is my opinion that the obstructions formed by the piles used in the repair will eventually effect, and it may be, very seriously, the channel of the river. A very distinguished engineer writes that "every obstruction temporarily placed in the way of the current, every attempt to guard one point by any artificial means, inevitably produces some corresponding change at another which can seldom be foreseen, and for which the remedy applied may be but a new cause of harm."

He continues to say that "no obstruction should be placed to the free ingress of the tides through all the channels." The many able reports written in years past generally agree upon the plan of removing all obstructions, even to the Long Bridge causeway. Colonel Abert, chief of the corps of topographical engineers, reports that this causeway has aided, in all the difficulties concerning the channels, the tendency to shoaling in all of them. He also states, "that the causway of the Long bridge is not the result of the plan of any United States engineer officer, but was adopted against the advice of all who were consulted upon that occasion; but the plan being made a positive direction of law, it had to be pursued in the construction of the bridge."

The causeway has proven a very great evil, but the injury done should not be accelerated by further obstructing the channel way.

Lieutenant Colonel Kearney, of the same corps, in his report on the Potomac bridge, writes as follows: "From the natural bed of the river, yielding as it does under the action of a very slight force, it must be apparent that the depth and course of the channels are not very constant, and accordingly our own observation made upon it united with tradition to confirm the opinion of extreme variableness. It is near the middle channel that, in former days, the river had worn for itself the deepest passage. We have penetrated the alluvial deposit to a depth of forty feet at that place. The action of a more rapid current than that which usually flows near the city shore, and one also which struck it very obliquely, is evinced by the bluff shores south of the Tiber. These observations are necessary to demonstrate the extreme care that should be observed in securing the foundations of the bridge, the requisite stability, and the caution with which we should avoid every unnecessary interruption of the current." From the several reports made by others who have examined, the general opinion is that all obstructions, whether they be of causeways, piles, or any other kind, excepting only those that are absolutely necessary for the support of the bridges, should be removed, so as not to interfere with the current of the river. The Potomac being a tidal river, the reason for doing so becomes still greater; for the same cause, as well as those above stated, all shoals should be deepened, and such

parts of the different channels, both above and below the bridges, as now tend to arrest the ascent and descent of the tidal wave, should be widened. So important has the improvement of tidal rivers become in Great Britain, that commissioners have been appointed to investigate the whole subject, and to inquire what measures it may be convenient to adopt for the general improvement of the harbors and rivers of the United Kingdom. The most stringent legislative measures were recommended by the tidal harbor's commission for the conservancy of the harbors and rivers.

I had the honor, general, on the 30th of April, 1868, to submit you a report on the examination or survey of the Potomac River, a copy of which is contained in the pamphlet marked C, pages 28 to 39, accompanying this paper. In that report the whole matter of the improvement of the channel is discussed. The following are some extracts from the same: "In anticipation of such improvements legal measures should be taken for remedying all existing injuries to the channels, for the conservation of the shores and harbors, for preventing further encroachments in the construction of such wharves as may produce any damaging effects. Every encroachment should be received with the greatest jealousy." In speaking of the removal of the causeway, the same report says that, "whatever opinion may be held or expressed by others in regard to the obstruction or encroachment in the river, in consequence of the building of the causeway of the Long bridge, it has been clearly demonstrated to me that there is no doubt that the structure is very injurious to the Washington channel, and that the section referred to should, therefore, be removed, and replaced by either an arched bridge or one of iron or wood. Those acquainted with the river have pointed out a marked increase, during the last ten years, in the dimensions of the flats, and consequent diminution in the depth and width of the channel. While the causeway obstructs to a considerable degree the water coming down from the interior of the country, it also partially prevents the tide water from coming up; it therefore interrupts that continual scour which should result from the force of the one and the flowing and ebbing of the other; the tides should have a perpetual and unrestricted current." The great object to be kept in view, in carrying into effect the improvement of the navigation of a tidal river, is the free admission of the greatest possible quantity of water from the sea, as reliance must be chiefly placed on the scour produced by the tide, and not on the current of the fresh water, as the chief agent in keeping open the navigable channel of the river.

Many celebrated engineers have concurred in the above opinion; and this being admitted, "it is manifest that all obstructions to the tidal flow upward should be removed;" such as shoals and bars, or dams and dikes, or any other cause of obstruction.

one.

The same reason that applies to a greater evil will apply to a lesser It would be impossible to ascertain the exact time or estimate the extent of such damage or injury, as so many unforeseen natural as well as artificial causes enter into the calculation. The only remedy is to remove as soon as possible the cause, if well established, of the evil now complained of, and in future to prevent its recurrence. The navigation of the Potomac is not a thing of to-day, but must live in the future, to aid in the promotion of the enterprise and enlightenment of a more advanced civilization and culture; its channels should be preserved and guarded with the utmost care against all encroachments. The problem has always been considered a most uncertain one, but infi