Marcus Hook, Pennsylvania; improvement of Wilmington Harbor, Delaware; repairing the stone piers belonging to the United States in the harbor of New Castle, Delaware; clearing and buoying the channel of the Schuylkill River; Ice Harbor at Reedy Island, Delaware; removal of obstructions of Salem River, New Jersey; improvement of South River, New Jersey; improvement of the north and south branches of the Shrewsbury River, New Jersey; survey of Horseshoe Shoals, Delaware River, Pennsylvania; survey of Chester Harbor, Delaware River, Pennsylvania, and survey of Delaware River between Trenton and Bordentown.

Very respectfully, your obedient servant,

J. D. KURTZ, Lieutenant Colonel of Engineers.

Brigadier General A. A. HUMPHREYS,

Chief of Engineers, U. S. A., Washington, D. C.

R 1.

DELAWARE BREAKWATER HARBOR.

The completion of this harbor, according to the original project, was reported in last year's annual report. This project was devised more than forty years ago.

It is the case here, as in many other Government works, buildings, and establishments, that the growth of the country has far exceeded the provision made for its probable wants. This harbor is quite too small for the accommodation of the vessels which now resort to it. Its position on the coast-line is admirable for the use it was designed to subserve, that of a harbor of refuge for vessels plying north and south along the Atlantic seaboard. It is situated just half-way from Sandy Hook Bay to the mouth of the Chesapeake, and vessels can enter it with very little deviation from their routes, and resume their voyages again with a minimum loss of time.

While the commerce of

It is a national work in the highest sense. Philadelphia and of all the other ports in the Delaware resort to it, a great number of other vessels, coming from and bound to ports outside of the Delaware, avail themselves of it just as freely, and take refuge in it from any stress of weather which makes it prudent for them to seek a harbor for a season.

Last year's report shows that fifteen thousand vessels were recorded as visiting this harbor. Adding those entering and leaving without being noted, twenty or twenty-five thousand may be taken as the number that used the harbor during the year. Its present capacity is determined by the space that is sheltered by the breakwater proper. This is a straight line nearly half a mile long, and it may be taken as the diameter of the half circle behind it, the area of which will represent approximately the sheltered harbor. Northeastwardly of the breakwater is the ice-breaker structure, a quarter of a mile in length, but separated from the breakwater proper by a gap of nearly equal extent, through which the sea rolls in northeastwardly weather without hinderance. If the sea which now rolls through this gap were excluded, the diameter of the sheltered area would be about doubled, and that area would be increased to between three and four fold its present extent. This would add very greatly to the capacity of the harbor.

A succession of careful surveys of the harbor shows plainly that the depth of water it affords has been sensibly and steadily diminishing since the great stone mounds which compose the works were formed. At the same time the point of Cape Henlopen has advanced to the north with remarkable rapidity, the shore having gained in that direction 600 feet in forty-three years, while the vertical deposit of sand has reached 50 feet. These facts exact the greatest caution in devising and executing additional works here, and call for very careful scrutiny of their probable and possible effects upon the harbor. Before the mode of shutting out the sea from the gap between the works is decided on, the subject should receive the consideration and study of more than one experienced engineer. My opinion is that the safest method is the preferable one. There will be opportunity now for a year's observation, by an engineer officer on the spot, of the action of sea, waves, currents, winds, and all the physical and meteorological features of the position, so that reliable data, running through the four seasons, may be collected, where so far it has been found impracticable to obtain definite particulars that can be relied on.

The three practical methods of enlarging the harbor are as follows: First. Fill the gap between the breakwater and ice-breaker with stone, uniting the two structures and making the whole a continuous barrier to the sea.

Second. Prolong the ice-breaker to the eastward till it laps the breakwater sufficiently to exclude the sea.

Third. Construct a detached work in advance of the gap of sufficient length to cover it at both ends.

The first method is the cheapest, but it prevents all access to the harbor by the gap, and requires vessels coming down the bay, as well as those going up, to pass to the southern end and enter between Cape Henlopen and the breakwater.

The third method allows access by the gap to vessels entering from either direction. Moreover, it interferes in the least degree with the currents and tides of the harbor, and so best avoids the risk of injuring the depth of water and of disturbing the shore lines.

A plan of the harbor, with sketches of the three projects here indcated, is transmitted with this report. This subject is fully discussed in the reports of Major Hartman Bache, Corps of Topographical Engineers, dated 15th October, 1844, 16th September, 1839, and others.

The views which I have presented are in accordance with those entertained by that officer.

It is recommended that there be appropriated for the service of the fiscal year ending June 30, 1873, for increasing the capacity of the Delaware Breakwater Harbor, or for continuation of operations at the Delaware Breakwater Harbor, $300,000.

R 2.

CONSTRUCTION OF PIER AT OR NEAR LEWES, DELAWARE.

The appropriation for the construction of a landing-pier at the Delaware Breakwater Harbor, was made at the close of the session of Congress in the summer of 1870. Ever since the construction of this b eakwater, by which an important artificial harbor of refuge was constituted at the mouth of the Delaware Bay, it has been very desirable for vessels using the harbor that convenient means of communicating with the shore should be provided for their use. A boat-pier was first constructed by the United States, and since its decay Congress has several times called for information as to the best means of replacing it. Recently a railroad has been constructed connecting the harbor with the region in its rear and with the general railroad system of the country. At the session of 1870-'71 an appropriation of $225,000 was made for the construction of a landing-pier of stone or iron at this locality. After the collection of all practicable information on the subject a project for a pier on wrought-iron screw-piles was submitted to the Chief of Engineers, and the proposed structure was approved by him, with the concurrence of a board of engineer officers in the project. Further information was

Number.

desired by the board before deciding upon the position for the pier. This information has been obtained, and the question of site may shortly be passed upon by it. In the mean time, such other measures as are practicable have been taken to expedite the work.

Arrangements have been effected for procuring the materials needed for the work; experiments on the soil, and the means of penetrating it, have been made; measures for securing a site from the State of Delaware have been effected, and such steps as will facilitate the determination of the legal questions concerned are in progress. Upon the transfer to the United States of the site for the shore-end of the pier, and the approval, by the Attorney General of the United States, of the action of the State of Delaware in the matter, the construction can be commenced. Abstracts of proposals for the iron and lumber for this pier are transmitted herewith.

To complete the structure the sum of $55,000 will be required, and it is asked that this sum be appropriated for the service of the next fiscal year.

STATEMENT OF FUNDS.

Appropriation by act of July 11, 1870...
Expenditures, (surveys, plans, services, &c.).

$225,000 00

3,992 50

221,007 50

Appropriation asked for year ending June 30, 1873.......

$55,000 00

Balance available July 1, 1871.......

Abstract of proposals—lumber for pier near Lewes, Delaware.

UNITED STATES ENGINEER OFFICE,
Philadelphia, Pa., April 5, 1871.

GENERAL: I have the honor to report as follows, upon the subject of the construction of "a good and substantial pier of stone or iron in the Delaware Bay, at or near Lewes, as provided for in section 12 of the act of July 15, 1870, (public, No. 183,) making appropriations for sundry civil expenses," and to submit the accompanying project for the construction of a pier, in compliance with your instructions of July 28, 1870, placing this matter in my charge.

As soon as the artificial harbor the of Delaware Breakwater came into use by vessels, the want of a landing-pier to enable them to communicate with the shore was realized; and provision was thereupon made by Congress for such a pier, to enable boats to land, provisions and supplies to be obtained, and to give access to the lines of travel and afford mail accommodations.

Accordingly, in 1837, a wooden-pile landing-pier was constructed by General (then Captain) R. Delafield, of the Corps of Engineers, for these purposes. This pier was about 1,200 feet long, with a uniform width of 20 feet, and had 8 feet of water at the pier-head at low water. The bays of the pier were 19 feet wide, with four rows of piles between them. The structure was guarded by a series of six ice-breaker piers on the seaward side, and a like series on the inner side, these piers being placed at distances of 75 feet from the landing-pier, and 100 feet to 150 feet from one ice-breaker to the next. This structure cost about $60,000, and lasted eleven or twelve years. It was not injured by the ice. A vessel adrift once broke through it, after the piles had been honeycombed by the boring-worms, which were the cause of its failing after twelve years' service.

In 1859 Lieutenant Colonel (then Captain) John Newton, Corps of Engineers, in compliance with instructions from the Chief of Engineers, presented a project for a landing-pier at the harbor. He proposed a wharf 90 feet by 90 feet, supported on 16 stone piles, to be connected with the shore by the shortest line, about north and south, the distance being a little over a thousand feet. The connection was to be a wooden trussed bridge 14 feet wide, with bays of a hundred feet, to be supported upon two sets of stone piers. Depth of water at the pier head 9 feet at low water. The stone piers to rest upon iron screw-piles. Colonel Newton presented his project as an illustration of the general principles upon which such a structure should be erected. The estimate of this project was $88,000.