difficulties have arisen in connection with the deposit of spoil upon League Island, and in the solution of that problem we have spent much time and energy, and a great deal of money. Our experiments and experience have demonstrated that the spoil is of such a nature that it could not have been dumped from cars except by the use of heavy streams of water; and even now powerful pumps must be used to throw streams of water into the scows to cut up the mud and in order to dump it from the scows. Finally, however, the big pulsometer has been completed, its defects have been remedied, and it has been in perfect working order for about ten days. During that period the pump has been timed, and has been found to put ashore at the rate of 1,000 yards of spoil per hour, and on one occasion it went as high as 1,500 yards per hour (750 yards in twenty-nine minutes by actual timing). The small pulsometer and the "Big Jim" are still upon the work, and have been depositing spoil. The capacity of the "Big Jim" when taking mud from the scows will, it is believed, be from 4,000 to 5,000 cubic yards per day, while the new new pulsometer can easily handle 10,000 cubic yards per day. Under these circumstances we feel, in view of the work actually done during the past ten days, that the question of putting the spoil ashore has been settled, and we have now turned our attention to the other end of the work. Circumstances have heretofore caused us to regard the filling in of League Island as the principal thing to be done, but we are now actively engaged upon what, of course, is the real work, the removal of Windmill Island.

Before the pulsometer was completed we had, at considerable expense, kept a large dredging plant upon the work, though we were obliged to keep it working just long enough to get out 1,500 or 2,000 cubic yards per day. That plant we have still here, but as all of our energies have been until recently devoted to the League Island end, we find the output of our dredging plant less than it would otherwise have been. Repairs and alterations are being pushed rapidly, and at the present time two dredges and five scows are almost ready to be again put to work. The following dredges are actually at work to-day, namely, the Columbus, America, Achilles, and Starbuck. On the 23d instant these dredges excavated 4,538 cubic yards during the usual working hours. Of this amount the Columbus dredged only 1,767 cubic yards, as she had not at the time succeeded in making a good bed for herself, and was, besides, working in a pile of old stone ballast. This dredge has, however, an actual record of 3,500 cubic yards per day, and we now expect her to average fully 3,000 cubic yards per day. The average daily capacity of the plant now at work, as shown by their actual performance, is about as follows:

Arrangements are being made for night work, and a part of the plant will work at night next week, so that the capacity of the plant now at work should then be about 9,000 to 10,000 cubic yards daily, at the very least.

In addition to this the Norwalk, now under repairs, will be ready for work in a few days, and has a capacity of 750 cubic yards; the Rattler, which met with an accident and sank a few days ago, has been raised, and is almost ready for work. Her capacity is 1,250 cubic yards per day, and she has repeatedly exceeded this amount on the present work. The actual capacity of the plant now on the work is, therefore, between 11,000 and 12,000 cubic yards daily. This output we expect to reach in a few days, and though our dredges have individually reached the amounts allotted to them, we have not yet reached our maximum capacity in one day for the following reasons:

(1) Because the Norwalk and Rattler are under repairs.

(2) Because so much of our attention has been devoted to League Island that our tug and scow service is not so well organized as it should be, or as it soon will be. (3) Because five of our scows have been temporarily taken from the work to have their dumping gear improved, as required by the nature of the spoil.

(4) Because we have not yet commenced night work.

In addition to the above-mentioned plant, we have just made arrangements to put upon the work a tugboat, six scows, and at least one dredge. This plant is already in the Delaware and will be at work early next week. When these scows are obtained the output of our present plant will be much increased.

If from any reason the capacity of our plant should prove less than we expect, we will obtain additional dredges. This, we believe, will be an easy matter, now that the pulsometer is at work.

With the plant now under our control, we expect to excavate and deposit 250,000 cubic yards of spoil during the month of July, 1892, and at least 300,000 cubic yards each month thereafter.

Very respectfully,

Maj. C. W. RAYMOND,

JAMES A. MUNDY & Co.

Corps of Engineers.

RECOMMENDATION.

UNITED STATES ENGINEER OFFICE,
Philadelphia, Pa., June 25, 1892.

GENERAL: I have the honor to transmit herewith a letter dated June 24, 1892, from Messrs. James A. Mundy & Co., of Philadelphia, asking an extension of time for the completion of certain work provided for in their contract for the improvement of Philadelphia Harbor, dated April 23, 1891.

The contract, as modified at the request of the contractors on July 6, 1891, by authority of Department letter dated June 27, 1891, provides for the removal of Windmill Island by dredging and scour to a level of 12 feet below mean low water, the amount of material to be thus removed, all of which is to be deposited on League Island, being estimated at 1,075,000 cubic yards, and for the removal of about 8,200 linear feet of piling and revetment inclosing the island.

By the terms of the contract, this work was to have been completed on or before December 31, 1891; but at the request of the contractors the time for completion was, on December 28, 1891, extended to June 30, 1892, by authority of Department letter dated December 26, 1891. The contractors state reasons for the delay in the work and ask a further extension of three months of time for its completion.

The total amount of work accomplished up to and including this date is as follows: Two thousand two hundred and thirty-three linear feet of piling and revetment have been wholly removed, and 1,020 linear feet have been removed to the level of low water. Three hundred and six thousand and fifty-seven cubic yards of material have been removed by dredging, 271,688 cubic yards of which have been deposited on League Island. The last survey, made during the present month, indicates that at least 25,000 cubic yards of material have been removed by scour above the 12-foot plane, making the total excavation about 331,057 cubic yards. This is less than onethird of the work required by the contract.

The contractors give as the cause of their delay the difficulties encountered in establishing a satisfactory plant for the depositing of material on League Island. These difficulties are fully recognized, but they do not furnish a satisfactory excuse for their failure to execute a considerable part of the work. The removal of revetment might have proceeded much more rapidly, notwithstanding the difficulties of depositing material at League Island, yet the contractors, although repeatedly urged to greater progress, have failed to accomplish this part of the work. During the past ten days an average of about 2,928 cubic yards have been dredged at Windmill Island and deposited on League Island. Had a suitable dredging and transporting plant been employed, three times this quantity might easily have been handled, for the depositing plant has been idle for want of material during a large part of the time.

The depositing plant established by the contractors at League Island now consists of three pulsometers, one of which pumps material from the bottom of the river and the others remove it directly from the scows. Owing to the character of the material, much difficulty has been experienced in adapting this plant to the work required. I am of the opinion that with proper management it can now deposit at least 10,000 cubic yards per day. The excavating and transporting plant is not now in a satisfactory condition, but it can be readily improved.

If this work is to progress in future at its previous rate it is not to the interest of the United States to continue this contract. The contractors, however, state in their application for extension that they "expect to excavate and deposit 250,000 cubic yards of spoil during the month of July, 1892, and at least 300,000 cubic yards each month thereafter." This is as rapid a rate of progress as is considered desirable under existing circumstances, and if it can be attained an extension of time for the execution of the work is believed to be to the interest of the United States. >

In view of the fact that the contractors have repeatedly made promises in writing which they have not succeeded in fulfilling, I have the honor to recommend that the time for the completion of the work specified be extended to July 31, 1892, with the understanding that if 250,000 cubic yards of material are removed from Windmill

ENG 92-58

Island and deposited on League Island during the month of July, as proposed by the contractors, an application for further extension will receive favorable consideration. Should this extension be granted, it should be understood that the United States retains its right to require the contractors to increase the monthly excavation to 400,000 cubic yards, as provided in the contract, should the circumstances of the work render such increase desirable.

Very respectfully, your obedient servant,

Brig. Gen. THOMAS L. CASEY,

C. W. RAYMOND, Major, Corps of Engineers.

Chief of Engineers, Ú. S. A.

APPROVAL OF RECOMMENDATION.

[First indorsement.]

OFFICE CHIEF OF ENGINEERS,

U. S. ARMY,
June 28, 1892.

Respectfully returned to Maj. Raymond, Corps of Engineers, approved, as recommended.

When such record as may be necessary has been made this paper will be returned to this office.

By command of Brig. Gen. Casey:.、

THOS. TURTLE,

Captain, Corps of Engineers.

PRELIMINARY PLAN FOR THE RECONSTRUCTION OF THE PHILADELPHIA WATER FRONT SUBMITTED BY MAJOR C. W. RAYMOND, CORPS OF ENGINEERS, TO THE BOARD OF HARBOR COMMISSIONERS FOR THE CITY OF PHILADELPHIA, PA.

PHILADELPHIA, PA., March 10, 1892.

DEAR SIR: In compliance with the request of the Board of Harbor Commissioners for the city of Philadelphia, expressed in a resolution adopted July 8, 1891, I have the honor to submit the following preliminary plan for the increase of the landing accommodations at this port:

The project for the improvement of the harbor of Philadelphia, now in process of execution by the United States, has for its principal object the readjustment of the main ship channel, so as to permit the widening of Delaware avenue and the extension of the piers along the water front of the city. This project was adopted by Congress in the act of September 19, 1890, and it requires the progressive extension of the solid filling and piers, during the progress of the work, as a necessary part of the improvement. Thus the early adoption of a plan for the reconstruction of the water front, and the commencement of its execution, are imperatively demanded both by the needs of commerce and the requirements of the project for channel rectification.

GENERAL CONDITIONS.

The preliminary plan of reconstruction now submitted as a basis for the discussions of the board has been prepared to conform to the bulk-head and pier-head lines conditionally established by the Secretary of War, January 20, 1891, in accordance with the provisions of the act of September 19, 1890, and to the conditions imposed by the adopted project for the harbor improvement.

The harbor lines were established "subject to the condition that wharves shall only be extended beyond the present legal port wardens lines, at such times and places as may be approved by the Secretary of War." They are included between Moore and Otis streets. The plan of reconstruction now under consideration, however, terminates at Shackamaxon street, since the lines between Shackamaxon and Otis streets may require readjustment, in view of recent legislation involving a possible change the location of the projected channel.

Specif attention is invited to the provisions of the act of September 19, 1890, under which the harbor lines have been conditionally established. The act provides that ❝where it is made manifest to the Secretary of War that the establishment of harbor lines is essential to the preservation and protection of harbors, he may, and is hereby, authorized to cause such lines to be established, beyond which no piers, wharves, bulk-heads, or other works shall be extended, or deposits made, except under such

regulations as may be prescribed from time to time by him." Under this authority the Secretary of War may prescribe regulations to govern the construction of all structures between the bulk-head and pier-head lines, should he consider such regulations essential to the preservation and protection of the harbor.

The plan of improvement adopted by Congress in the act of September 19, 1890, requires that the solid filling shall in due time be carried out to the new bulkhead line throughout the whole extent of the water front, and that a sufficient number of piers prolonged or newly constructed shall at proper times be extended to the new pier-head line. These conditions are imperative, for they were assumed in determining the cross-sections, channel volumes, and location of the deep-water line which form the basis of the plan established by law.

It is, however, neither necessary nor possible to fully effect the contemplated changes in the immediate future, but regulations governing the method of reconstruction in conformity with these conditions should now be adopted, and no future constructions should be permitted on the water front which are not in accordance therewith.

The establishment of regulations conforming to the conditions above stated involves the consideration of questions which are as difficult as they are important. It is necessary to determine what number of piers will be sufficient to extend to the pier-head line, whether the partial extension of any piers will be permissible, and in what way the method of pier construction adopted will exert an influence upon the channel. These questions have been investigated theoretically, and also by a laborious study of the changes in the river itself. A very brief statement of the problem and the results obtained, to indicate the part played by the reconstructed water front in the general scheme of ratification, is all that can be attempted in this report.

STATEMENT OF THE PROBLEM.

The

If we suppose the islands and shoals removed, the Petty Island channel widened and solid quay walls built continuously along the pier-head lines of the Philadelphia and Camden shores, we shall have the theoretical rectification which formed the basis of the plan of the board of 1888. The river will be able to permanently maintain its cross-section at every point. The line of deep water will be a smooth and uniform curve near the Philadelphia quay wall and nearly parallel to it. advance of the Camden shore and the change in the direction and quantity of the ebb current will be the principal agents working to prevent the re-formation of the islands and shoals, while the advance of the Philadelphia shore will have simply corrected the irregularities of the deep-water line and moved it nearer to the line of midchannel. It is important to notice that an advance of the shore on the convex side produces a scouring effect which extends much farther into the river than an advance on the concave side. This is very plainly indicated by a comparison of all the existing charts.

The advance of the Philadelphia shore line, therefore, so far as it relates to the scheme of channel improvement, has for its object to locate and hold the deep-water line in a proper position rather than to compensate for an increase of channel volume resulting from the removal of the islands and shoals. The depth along the deepwater line is not a matter of importance, since it is sure to be greater than necessary whatever conditions may exist, but the form and location of the deep-water line are matters of great consequence, since this line indicates the character and uniformity of the channel. If the deep-water line exhibits violent and irregular bends, instead of following a smooth and uniform curve, we know that the channel will be irregular and can not be permanently maintained under the action of the ever varying forces at work upon it.

If we now substitute for the solid quay wall along the Philadelphia shore a system of piers separated by considerable distances from each other and extending to the pierhead line, the deep-water line will be deflected inward between the piers. If shorter piers not extending to the pierhead line are constructed in the intervals, the irregularities in the deep-water line will be greatly increased. If the short piers are omitted and the long piers are brought sufficiently near to each other, the deepwater line will be brought practically into coincidence with the location determined by a solid wall. If the piers are of an open construction, permitting a free flow of the currents, a regular deep-water line may be maintained with wider dock intervals than when the piers present solid obstructions inducing irregularities in the movement of the water.

These statements are strikingly illustrated by the hydrographic surveys of 1843 and 1890. In 1843 the number of piers on the water front between Washington avenue and Green street was 80, only 15 of which extended to the pierhead line. The deepwater line presented great irregularities. In 1890 the number of piers in the same interval was 69, of which 42 extended to the pierhead line. Although irregularities still exist in the deep-water line, its uniformity has been greatly improved, in spite

of the fact that the waterway has been unduly narrowed, and the average dock interval has been increased.

It may be considered established that the principal cause of hurtful irregularities in the deep-water line is variation in the lengths of the piers. Too great a width between the piers is also a secondary cause of deflection, but the existing conditions are so complicated by the presence of the islands and shoals that the greatest interval between piers which can be permitted without injury to the form of the channel can only be determined by observations during the progress of the rectification. It is certain, however, that greater intervals may be adopted with open piers than with those which present solid obstructions.

CONDITIONS FOR THE PLAN.

The conditions, therefore, which are imposed upon the plan of reconstruction by the project for channel improvement adopted by the United States are as follows: 1. The plan must assure the ultimate extension of solid filling to the established bulkhead line throughout the whole extent of the water front.

2. It must assure the construction or extension of a sufficient number of piers to properly establish the deep-water line; it must require the full extension to the pierhead line of all piers necessary for this purpose; and it must prohibit the partial extension of piers, at least until the new conditions of the channel have been fully determined.

3. It must assure the adoption of methods of pier construction which will permit so far as possible a free movement of the currents.

These conditions will doubtless be enforced to some extent through regulations of the War Department, to be established under the provisions of the act of September 19, 1890, as will be hereafter more fully explained.

Thus far I have considered the problem merely in its relation to the work of improvement undertaken by the General Government; but other important considerations relating to the present and prospective needs of commerce must receive attention in the preparation of a plan for the increase of the landing accommodations of the port. The extent of the water front is limited. A plan which would furnish ample accommodations for the business of the present day might prove inadequate to satisfy the demands of commerce in the future, the extent of which it is now impossible to foresee. The history of similar undertakings in other ports of the world gives us a right to anticipate an enormous increase in the business of the port when its improvement has been completed and a permanent deep-water channel has been established to the sea. It is therefore important that the plan adopted shall so utilize the whole water front as to accommodate in the best possible manner all the present and future commercial interests of the city. To this end the conditions which should regulate the arrangement and dimensions and the methods of construction of the piers and docks should be determined.

It appears to be the general opinion of those having the most experience in matters of transportation that a width of about 80 feet for piers is best adapted to the general purposes of commerce. This width permits a double track along the axis of the pier with temporary storage spaces of sufficient capacity on each side. The docks or water spaces between the piers should be of sufficient width to permit large vessels to lie at both piers and coal on both sides at the same time, leaving a space between for passage to the wharf at the bulkhead line. A width of 250 feet is not too great for these purposes. It is, however, desirable to utilize existing structures so far as possible, and to interfere with private interests only where such interference is unavoidable. In the plan now submitted, therefore, the minimum width of piers has been taken at 75 feet and the maximum width at 100 feet, and I have sought to obtain a dock width of about 200 feet, except in special cases. The plan has been prepared in the following manner:

PREPARATION OF THE PLAN.

1. An accurate map of the water front was constructed from data obtained from the U. S. Engineer Office and the office of the city engineer. Upon this map the harbor lines of the United States, showing the future limits of open and solid filling, were carefully laid down.

2. The names of the riparian owners were obtained from official sources, corrected by personal inquiry, and recorded on the map.

3. A preliminary or trial plan of a system of piers was prepared so as to conform as far as possible with the conditions above established, keeping in view the desirability of utilizing existing structures and interfering as little as possible with private interests.

4. The water front was divided into sections of convenient length, and plans, on a large scale, were prepared, showing for each section the existing water front and