55th Congbess, ) HOUSE OF EEPEESENTATIVES. ( Document 3d Session. ] \ No. 159. EAST CHANNEL, NEW YOEK HAEBOE. COLUMBIA LIBRARIES OFFSITE LETTER AR01500414 from THE SECRETAEY OF WAR, TRANSMITTING A LETTER FROM THE CHIEF OF ENGINEERS, WITH COPIES OF REPORTS RELATIVE TO SURVEY OF THE EAST CHANNEL, NEW YORK HARBOR, FROM THE NARROWS TO THE SEA. January 18, 1899. — Referred to the Committee on Rivers and Harbors and ordered to be printed. War Department, Washington, January 17, 1899. Sir : I have thehonor to transmit herewith a letter from the Chief of Engineers, United States Army, dated January 16, 1899, together with copies of reports from a Board of Engineers and Lieut. Col. Wil- liam Ludlow, Corps of Engineers, dated respectively December 16 aud April 5, 1898, of a survey of the east channel. New York Harbor, from The Narrows to the sea, made by them in compliauce with the provi- sions of a joint resolution of Congress, approved January 12, 1899. Very respectfully, E. A. Alger, Secretary of War. The Speaker of the House of Eepresentatives. Office of the Chief of Engineers, United States Army, Washington, D. C, January 16, 1899. Sir: Joint resolution of Congress, approved January 12, 1899 (Pub- lic resolution No. 7), directs the Secretary of War "to submit a report of survey aud estimate for the improvement of the east channel in New York Harbor from The Narrows to the Sea, and for the enlarging of the same to the depth of thirty-five feet and a width of one thou- sand five hundred feet, and to also report upon the desirability of such improvement." To enable the Secretary to comply with the provisions of this reso- lution, I have the honor to submit the accompanying copy of report, dated December 16, 1898, by a Board of Engineers, in relation to the subject. 2 f^m EAST CHANNEL, NEW YORK HARBOR. It is the opinion of the Board that a channel at least 35 feet deep at mean low water and 2,000 feet wide should be provided, and that, for reasons stated in the report, the east channel should be the one to be dredged. It is estimated that a channel of such dimensions would cost $4,510,000, but, in view of the anticipated construction of vessels of deeper draft, resulting in diminished cost of transportation, the Board is of the opinion that the proposed channel should ultimately be * deepened to 40 feet, and submits an estimate therefor amounting to $6,088,000. The resolution calls for an estimate for a channel 35 feet deep and 1,500 feet wide, while the report and estimate of the Board are for a channel 2,000 feet wide. Detailed information regarding the narrower channel is not at hand, but it can be considered as approximating three- fourths of the cost of the 2,000-foot chaunel. The views of the Board are concurred in by me. There is also submitted herewith a copy of a report, dated April 5, 1898, with map, by Lieut. Col. William Ludlow, Corps of Engineers, (now major-general, U. S. Volunteers), upon survey for obtaining a main ship channel from the Narrows to the sea, with a depth of 35 feet at mean low water. It may be said in explanation that the board, whose report is sub- mitted herewith, was constituted, by authority of the Secretary, for the purpose of considering and reporting upon the ab.ove-mentioned com- munication of General Ludlow, and that the communication of Decem- ber 16, 1898, herewith, is the Board's report thereon. Very respectfully, your obedient servant, John M. Wilson, Brig. Gen., Chief of Engineers, TJ. S. Army. Hon. B. A. Alger, Secretary of War. survey of the east channel, new york harbor, from the narrows to the sea. United States Engineer Office, New York, N. Y., December 16, 1898. General : The Board of Engineers, convened by Special Orders, No. 22, headquarters, Corps of Engineers, September 12, 1898, to consider and report upon the question of securing a channel of adequate depth and width to accommodate the commercial interests centering at the port of New York, have the honor to submit the following report: The Board met pursuant to the call of the senior member in this city December 16 and carefully considered the reports and maps of the recent surveys made in accordance with the last river and harbor act. The deepest draft of steamers which now make use of the harbor is 32 feet, and it is stated by steamship agents that larger vessels are under construction, which will draw, when loaded, as much as 33 feet. A list of deep-draft vessels is appended. For vessels of this class a channel at least 35 feet deep at mean low water and 2,000 feet wide should be provided. The Board is further of the opinion that the east channel should be the one to be dredged, for the following reasons: First. Shorter distance. — The course between New York and the ocean is 5 miles less by way of east chaunel than by way of main ship channel. EAST CHANNEL, NEW YORK HARBOR. 3 Second. Avoiding sharp bends. — In east channel the bends are slight. Between the south end of main ship channel and west end of Bayside Channel is a bend of about 115° in a distance of 0,000 feet. In unfa- vorable conditions of currents, winds, and low water it is not easy for a deep-draft vessel, with keel near the bottom, to turn within narrow limits. Third. Straight currents. — In east channel the currents are straight, or nearly so, as far as observations show. In Gedney and Bay .side channels they are about true, but in main ship channel they are cross. The cross currents, however, are not strong, even at maximum. Tlie following estimate for a channel 2,000 feet wide and 35 feet deep is submitted: Four dredges, at $200,000 each $800, 000 Dredging 33,000,000 cubic yards, at 10 cents 3, 300, 000 Add for contingencies 10 per cent 410, 000 Total 4,510,000 The reported cost of recent work of dredging at the mouth of the Mersey, the entrance to Liverpool Harbor, is less than this, but it is doubtful if contractors in this country will undertake the work for less than the estimated cost. In view of the construction of vessels of deeper draft, which diminish the cost of transportation, the Board is of the opinion that the proposed channel should ultimately be deepened to 40 feet, and the following estimate of cost is submitted: Four dredges, at $200,000 each $800, 000 Dredging 52,800,000 cubic yards, at 10 cents 5, 280, 000 Add tor contingencies 10 per cent b'08, 000 Total 6,688,000 Henry M. Robert, Colonel, Corps of Engineers. O. W. Raymond, Lieutenant- Colonel ', Corps of Engineers. H. M. Adams, Major, Corps of Engineers. Brig. Gen. JoriN M. Wilson, Chief of Engineers, U. S. A. Vessels of SO feet draft or over passing out over Sandy Hook Bar, January 1 to December 3, 1S98. Name of steamahip line. Hamburg- American Line . American and Red Star Line , White Star Line , Name of vessel. Palatia Prel oria Phoenicia Pennsylvania . Brasilia Patria Bulgaria Southwark Cymric Number of trips. 30 feet draft or over. mum draft. Ft. in. 30 Number of vessels. . . Number of trips out. Maximum draft 9 25 .feet.. 32 H. Doc. 65 24 4 EAST CHANNEL, NEW YORK HARBOR. The following steamers of estimated draft 30 feet or over are reported building: Red Star Liue, 2 steamers, estimated draft 30 feet +; ready in 1900. White Star Line, 3 steamers, estimated draft 30 feet +; ready in 1899. Hamburg-American Line, 5 steamers, estimated draft 30 feet +; ready in 1899. Atlantic Transport Line, 4 steamers, estimated draft 31 feet to 33 feet; ready in 1899. Cuuard Line, 2 steamers, estimated draft about 30 feet; ready in 1899. report of lieut. col. william ludlow, corps of engineers (now major-general, united states volunteers). Engineer Office, United States Army, New York, N. Y., April 5, 1898. General: I have the honor to submit the following preliminary report of the resurvey of New York Harbor, made pursuant to the act of June 3, 1896, which called for surveys and estimates of the cost of obtaining a main ship channel from The Narrows to the sea, with a depth of 35 feet at mean low water. The late date at which the organization of the field party was finally effected, and the delay due to unfavorable weather during the fail mouths into which the survey was necessarily prolonged, have made it impracticable to procure the complete data required for a full discus- sion, and the pressure of other urgent matters requiring attention at this time prevents making entire use of the material collected. The remaining information, however, principally borings, can be readily supplied later, and is not essential to the statement of the cost of secur- ing the channel in question, and the fuller report can be hereafter pre- pared in time for incorporation in the next annual report. For the detail particulars of the survey, I beg to refer to the accom- panying preliminary report by Mr. Stierle, assistant engineer, who lias had charge of the work under my direction, and whose prolonged expe- rience in studies of this kind lend value to his statements. The accom- i panying chart has been drawn on a scale of 1 to 20,000, and by use of colors for the submerge d contours exhibits clearly the hydrographic conditions and status of the harbor entrance. The width of the open- fog between Sandy Hook and Coney Island is 7 miles, and the green contours of 12 feet depth, indicating the several banks or shoals which separate the oceau from Karitau Bay, show the general position of the crest of the main bar. This bar is traversed by several channels of varying nature and depth, which represent the resultants of the numer- ous and complex hydraulic and tidal conditions affecting the entrance. The Coney Island Channel close under the land has all the charac- teristics of a flood tide channel; that is, a channel mainly controlled , by the action of the flood current. These features are the gradual shoaling of the channel from the sea, and the existence of a bar at its inner end. The 14-foot channel is mainly an effect of the ebb tide, the [ force of which is lost soon after crossing the main crest of the bar. The east channel is a well-marked result of the ebb current, and carries to sea the greater proportion of the outflow from the Upper Bay and the Hudson Kiver Basin, through The Narrows. It is, in fact, the old bed of the Hudson Kiver, and maintains naturally a broad channel of over 30 feet depth for a distance of 4£ miles below the 35 foot contour of the deep water south of The Narrows, passing completely through the main crest of the bar, and leaving an interval of If miles between the lower or sea end of the 30-foot channel and the corresponding contour on the ocean floor. This interval constitutes the bar in the east channel. EAST CHANNEL, NEW YORK HARBOR. 5 The Swash Channel is a subsidiary channel or cut-off, lying between the east and Bayside channels and partaking of both ebb aud flood characteristics. It crosses the latter channel at a considerable angle, and its natural prolongation seaward is designated the south channel. The Bayside Channel tonus a deep pool off the north end of Sandy Hook, due mainly to the powerful outflow of the tidal prism of Raritau Bay. which is crowded southward by the general ebb movement from The Narrows. Its continuation to sea is by means of the Gedney Channel, which is partly artificial — that is, has been deepened by dredging. After enter- ing by the Gedney aud traversing the Bayside Channel the course of essels bound for New York is by means of a narrow and partially arti- ficial channel northward from the Southwest Spit to the deep water below The Narrows. This last chanuel is at nearly right angles with the general move- ment into aud out of Raritan Bay, aud in consequence of the tides cross- ing it there is a constant tendency to fill, and the full depth can be maintained only by dredging Between Southwest Spit and Sandy Hook there is also a marked and general tendency to form a bar obstructing the Bayside Chanuel, which requires frequent atteution from the dredge. This shoaling is due to the gradual westward extension of Sandy Hook and the effect of the flood current sweeping around the point of the Hook and depos- iting sand uuder its lee. At the present time the main ship channel enters the Gedney, turns the angle iuto the Bayside. turns an acute angle again around South- west Spit, aud thence goes northward to The Narrows. As is shown by the red contours of 30 feet depth, the 30-foot channel is continuous throughout the course indicated, though iu several places the 30-foot contours are less than 1,000 feet apart. The distance from the 35-foot contour below The Narrows to the same contour at sea outside the Ged- ney is 11^ miles, the channel widths and depths varying greatly over this distance, about 8 miles of which, to a greater or less extent, require dredging for deepening and maintenance. When the improvement of the New York entrance to 30 feet at mean low water was undertaken, iu 1884, the original appropriation was spe- cifically for deepening the Gedney Chanuel. without prior report by the engineers of the War Department. The Gedney being specified by the act, left the choice of a continu- ance of the deepened navigation, either by the Swash or by following the Bayside to Southwest Spit and thence northward. The character- istics of the Swash — its narrowness aud lumpiness, and its close vicinity to the Homer, which is the shoalest place on the main crest of the bar — discouraged its adoption as a main channel; and iu addition the ques- tion of military defense and the expediency of bringing heavy vessels uuder the guns of Sandy Hook were considerations not without weight. At this time, with a new proposition to make a 35-foot low-water navi- gation, the act does not restrict the consideration of the general sub- ject of location, and the important question at the outset is as to where the future channel should be made, so as best to meet requirements, conserve the interests concerned, aud produce the most advantageous results with the least expenditure of time aud money and the best guarantee for future maintenance. There is no question, in my judgment, that the east channel, is in nearly every respect the most favorable. It is the natural main outlet for the ebb tide through The Narrows and the deepest and widest 6 EAST CHANNEL, NEW YORK HARBOR. natural channel across the bar. By virtue of its powerful discharge and the directness and uniformity with which the tidal currents, both of ebb and How, traverse it, the east chanuel has always maintained its natural superiority without artificial aid, and lias in fact poshed its deep contours seaward and somewhat deepened its passage over the bar at the outer end, notwithstanding the artificial widening and deepening of the main ship channel. To open tins chanuel to the sea is a comparatively simple task, and a comparison of the quantities of dredging involved in deepening the east channel to 35 feet, with a width of 2,000 feet, and of effecting the same enlargement of the present ship channel shows a materially less amount in the former case, with the advantage that most of the.diedging will be done at the outer end, near the place of deposit at sea, and with the special advantage of greatly increased probabilities of maintenance, and hence a notably diminished cost on this account. I have, therefore, no hesitation, from the engineering and economic standpoint, in recom- mending the east channel as the best location for the main ship channel of entrance to New York Harbor. From the commercial standpoint the advantages are even more con- spicuous. The east channel is at once the most direct, the shortest, and the most commodious, and the tidal currents, both ebb and Hood, run true. The distance between the 35 foot contours, inside and outside, is miles— 5 miles less than by the present ship channel. The straight axis of 4 miles of its sea end, as drawn on the chart, can be marked by a light-house on its prolongation on West Bank, and the subsidiary lighting would offer no difficulty. The upper entrance is given a fun- nel shape, enlarging by a gradual curve from the straight portion 2,000 feet wide into the deep-water section above, with a width of over 4,000 The total quantity to be dredged from the east channel to make a channel 2,000 feet wide and 35 feet deep at mean low water, including allowances of 1 foot overdepth, side slopes of 10 to 1, and 25 per cent added for difference between scow and place measurement and for the wash and tilling in during construction, is 29,100,000 cubic yards. The material is sand, gravel, aud mud, all readily dredged by pumping. These materials, with suitable appliances, have been removed and deposited at from 3| to 7 cents, according to circumstances. In the case of New York Bar the dredging steamer deepened the Gedney Chanuel at a cost of about 5 cents, the work on the interior channels costing about twice that. I have therefore used 7J cents, with 10 per cent added for contingencies, as a reliable unit price for the east channel work on the scale in question. For the construction of the channel powerful dredges are desirable, both for economy and expedition, and I have allowed for four of these, which would make the channel completely in from two and one half to three years, and by reason of the greater natural depth of the north half of the channel as designed could open it for a width of 1 ,000 feet and depth of 35 feet in about one and one-fourth years. The estimate therefore stands as follows: Dredging 29,100,000 cubic yards, at 7J cents $2, 182, 500 feet. Contingencies, 10 per cent 218, 250 4 pump dredges, at $200,000 2, 400, 750 800, 000 Total 3, 200, 750 EAST CHANNEL, NEW YORK HARBOR. 7 This sum represents estimated net cost at prices that are ample to cover all expenditures. If the work be given out at contract an increase of about 20 per cent should be allowed, and the total would be $3,840,900. If the United States do the work the contractors' profit will be saved, and the dredges will remain public property. Upon completion of the channel one of the four could be retained for maintenance and the remaining three assigned to other work. An incidental advantage of opeuing the east channel would be the freedom from interference by vessels, as the present ship channel would be maintained while work was in progress in the east channel. As heretofore indicated, all the circumstances favor the east channel with the exception possibly of the military defense question. The east channel lies about midway between Coney Island and Sandy Hook, and is therefore, on the average, about 3i miles distant from either — range fully within reach of modern ordnance, but somewhat greater than has been regarded desirable in connection with torpedo defense and the protection of the torpedo fields from interference. But this objection can be met by special means, and it is quite likely in any case that the Bomer may be occupied hereafter by a suitable armament, when the objection would be entirely relieved. Further- more, as a general proposition, since hostilities are abnormal and excep- tional and commerce is habitual and constant, it seems evident tliat iu an instance such as the most important and valuable harbor in the country, the maintenance of whose commerce is vital, the dispositions as to the channels of entrance and exit should be such as to facilitate to the utmost the movements and security of shipping, even if some disadvantage should accrue to the details of a military defense. Your obedient servant, William Ludlow, Lieutenant- Colonel, Corps of Engineers. Brig. Gen. John M. Wilson, Chief of Engineers, U. S. A. [First indorsement.] Office Chief of Engineers, U. S. Army, September 6, 1898. Respectfully submitted to the Secretary of War. The river and harbor act of June 3, 1896, provides for survey of New York Harbor from The Narrows to the sea, with a view of obtaining 35 feet at mean low-water mark, and under this provision of law a report aud estimate prepared in January, 1897, by Col. G. L. Gillespie, Corps of Engineers, the officer then in local charge of improvement of New York Harbor, was submitted to Congress, and is priuted in House Doc. No. 243, Fifty-fourth Congress, secoud session, and in the Annual Beport of the Chief ot Engineers for 1897, pages 1053 et seq. After this report was presented it was thought advisable that the creation of a new channel, differing in location from that now in use, and other portious of the subject should have some further considera- tion, and Lieut. Col. Wm. Ludlow, Corps of Engineers, the successor of Colonel Gillespie, prepared and submitted the within report of the results of a survey of the locality mentioned. The question of securing a channel of adequate depth and width to accommodate the vast commercial interests centering at the principal 8 EAST CHANNEL, NEW YOKK HARBOR. port of the United States is one of paramount importance, and while it is questionable whether, in view of the provisions of section 4 of tlie river and harbor act of June 3, 1896, this second report on the subject of the survey mentioned can be properly submitted to Congress with- out further legislative action, it is certainly desirable that this office be in possession of all important and available data respecting the channel approach to the city of New York, and in my judgment the matter should receive the careful consideration of a Board of Engineer Officers in order that the fullest attainable information may be access- ible to the committees of Congress. I have the hotior therefore to recommend that these papers be referred to such a board for consideration and report, the board to consist of Col. H. M. Robert, Corps of Engineers; Lieut. Col. C. W. Raymond, Corps of Engineers, and Maj. H. M. Adams, Corps of Engineers. With the sanction of the Secretary the order constituting the board will be issued by his direction from this office. John M. Wilson, Brig. Gen., Chief of Engineers, U. S. Army. [Second indorsement.] War Department, September 8, 1898. Approved as recommended by the Chief of Engineers. By order of the Secretary of War : John Tweed ale, Chief Clerk. •[Third indorsement.] Office Chief of Engineers, U. S. Army, September 13, 1898. Respectfully referred to Col. Henry M. Robert, Corps of Engineers, for consideration and report by the Board of Engineers constituted by Special Orders, No. 22, headquarters, Corps of Engineers, September 12, 1898, of which he is the senior member. The Board is authorized to call upon the local officer for any previous reports it may desire or for any additional information deemed neces- sary, and the expenses of the Board will be paid by Maj. II. M. Adams from appropriation for improving New York Harbor, New York. It is desired that this subject receive that thoughtful and careful consideration which its importance demands, and that the report of the Board be submitted at the earliest practicable date consistent with the other duties devolving upon the members of the Board, and with proper consideration of the important questions involved. By command of Brigadier-General Wilson: A. Mackenzie, Lieutenant-Colonel, Corps of Engineers. [Fourth indorsement.] Army Building, New York City, December 17, 1898. Respectfully returned to the Chief of Engineers, inviting attention to inclosed report of this date. Henry M. Robert. Colonel, Corps of Engineers. EAST CHANNEL, NEW YORK HARBOR. 9 report of assistant engineer a. stierle. Engineer Office, United States Army, New York, N. T., March 31, 1898. Sir: I have the honor to submit the following preliminary report upon the survey of New York Harbor from The Narrows to the sea, with a view of obtaining 35 feet at mean low water, which was made under your direction : The organization of the held party was completed about July 1, pursuant to authorization by the Chief of Engineers, dated June 28, and after the necessary preparations had been made, such as chartering boats, erecting tide gauges, etc., active operations were begun on July 7. The information to be brought out by the survey was to embody principally all changes, if any, in the hydrography between The Narrows and the 40-foot contour outside the bar; the prevailing direction of the tidal wave and its rate of propaga- tion by tidal observations at several poiuts; the direction and volume of currents across the bar; all changes in the shore lines adjacent to the bar, Sandy Hook, and Coney Island, respectively; and the determination of the character of the bottom by borings aloag and in the vicinity of the east channel. As the season most favorable for such work was already well advanced, it required unremitting attention to make the best use of the time remaining before rough weather should set in. The progress of the survey was further delayed by frequent squalls during the summer and a series of windy days during the fall, so that not until December 1 was the work sufficiently advanced to permit of disbanding the held party. The data obtained by the survey are less complete than is desirable, especially those relating to current observations and borings, which, however, can be supple- mented later. Meanwhile it is of importance to embody in the present report all such observations and deductions noted since the recent chart has been plotted which are of general interest and which will directly affect proposed improvements. The area covered by the survey extended eastward to about the meridian of Rock- away Inlet: westward to include Old Orchard Shoal, the West Bank, and The Nar- rows; southward, in the bay as well as offshore, to the latitude of Horseshoe Cove, Sandy Hook, and northward to The Narrows, a total of about 80 square miles. Soundings were first taken over the whole ground along lines running as nearly as practicable east and west and north and south, followed later by special examina- tions of each channel, with the number of soundings greatly increased and the courses of the boat held closer together. In all, 18,000 soundings were taken, and as every alternate one was located by two sextant angles, the number of angles observed is about the same. For reduction to mean low water the established plane at the engineer wharf at Sandy Hook was used, to which also all other tide gauges set up iu the upper part of the bay were referred, proper cognizance being taken at certain stages of the tide, particularly during the ebb, of the prevailing slope. Shortly after the survey was begun certain members of the field force were detailed for special work on shore during days too unfavorable for work on the water. This party succeeded before the season was over in making a complete detailed survey of the portion of Sandy Hook situated north of Horseshoe Cove, and of the entire south shore, including adjacent topography, of Coney Island. A chart embodying the results has been plotted to a scale of 1:20,000 — the same scale as that of the survey of 1884, to permit of an easy comparison. This informa- tion was subsequently enlarged in part to a scale 1:5,000 for special purposes, the reductions, each on a separate sheet, covering the whole of the east channel, the northwest shoal iu Bayside Channel, the so-called Coney Island Channel, and the hydrography around the northern part of Sandy Hook. Detailed maps of the surveys of Sandy Hook and Coney Island were also plotted upon the same scale — 1:5,000. Continuous tidal observations were made throughout the survey at Horseshoe Cove, Sandy Hook, aud Fort Hamilton, the registering being done by automatic tide gauges. These observations are still continued. A tide record was also kept at Old Orchard Shoal Light-house for three months, and occasionally at the engineer wharf, Sandy Hook, at Norton Point, Coney Island, and at Swinburn Island. The notes have been compiled and are now in preparation to be tabulated. They have received a valuable addition, covering the period of our observations, in the records of an automatic tide gauge at the United States light-house depot, Staten Island. Comparing the present chart witli that of 1884, a tendency to shoaling is shown by the soundings along the west side of the main ship channel north of Southwest Spit. There are unmistakable indications that the shoal in the Bayside Channel northwest from Sandy Hook is re-forming, the width of the dredged channel having been reduced and the depth diminished since dredging was suspended in 1895. Considerable shoaling has taken place on the west side of the point of Sandy Hook, due to a westerly extension amounting to 1,270 feet since 1884. There is apparently 10 EAST CHANNEL, NEW YORK HARBOR. a tendency to connect with the northwest shoal, and thence with Southwest Spit across the present main channel. The Gedney Channel seems to have fairly main- tained its depth. The shoal called the False Hook, outside .Sandy Hook, has deep- ened. False Hook Channel, however, remains the same. The Romer Shoal and Swash Channel show only slight changes, confined to locally small areas. The east channel deepened at the outer end near the bar and over the latter. The crest of the east bank, and, in fact, those of all shoals north of the oast channel up to the Coney Island shore, show more water than formerly, but have shifted southward. The middle portion of Fourteen-foot Channel has shoaled and also moved southward. In the deep-water pocket between Rockaway Inlet and the east bank all contours deeper than 18 feet have moved out considerably; in some places, where over ten years ago the depth was 30 feet at mean low water, it is now only 20 feet. This change maybe directly attributed to the enormous quantities of city refuse being dumped in this vicinity. The western end of Coney Island has extended westward about 280 feet since 1884, but in other respects the Coney Island Channel is substantially unchanged. Curreut observations were made during the few calm days that occurred while the survey was in progress opposite Gravesend Bay, near eastern side of the main channel, in the Coney Island Channel, in the east channel, and in the main ship channel opposite Sandy Hook. The observations were carried on in each case throughout a full run of a tide with submerged floats suspended at middepth. The results were subsequently reduced to a mean stage of the tide, and from these, together with observations made by the Engineer Department and the Coast Survey on previous occasions at other points, the mean velocity of both Hood and ebb cur- rent for each channel was determined. The cross sections of the channels were measured along a line joining the shoalest points of the adjacent bars. It was found that during the ebb current — the one which principally forms the channels — the east channel has the greatest mean velocity, viz, 1.91 feet per second, and that the Bayside Channel is next, with a mean velocity of 1.63 feet per second. The mean velocity during flood is slightly larger in the last-named channel than in the east channel, being, respectively, 1.70 and 1.65 feet per second. The velocity curves were plotted upon one sheet, together with a tidal curve representing the mean rise and fall of the tide at Sandy Hook. This diagram shows the velocity in any chan- nel at any moment with reference to the stage of a normal tide at Saudy Hook, and illustrates the momentum, gained by a free movement, of the ebb and flood currents in the east channel, both continuing for a considerable period after the currents in the channels have become slack. It would be well to supplement these current observations with an additional series taken in the fourteen-foot Channel, and probably in the two subsidiary channels just north of it, as without these no accurate estimate of the whole discharge over the bar can be made. The Coast Survey* estimated the total discharge in 1858 at 27,663,000,000 cubic feet, modified in 1872 to 26,756,000,000 cubic feet, which estimate included the tidal prism of Newark and Raritan bays and the Kills, and the Hudson and part of East River. Adopting for comparison 27,000,000,000 as a basis, the gap in our observations can be easily filled, and the resulting discharge, expressed in percentage of the whole, is as follows : Main ship (Bayside) channel, ebb, 19 per cent; flood, 22 per cent; east channel, ebb, 26 per cent; flood, 2-1 per cent. As directed, I have made an estimate of the amount of material to be removed from the east channel, based upon data of the recent survey, for a channel 2,000 feet wide and 35 feet deep at mean low water along the lines shown on the accompany- ing chart. The net amount of the prism in place, inclusive of 1 foot overdepth and side slopes of 1 to 10, is 23,2(56,240 cubic yards. Adding 25 per cent for filling in of material from the adjacent shoals during the progress of dredging or during tempo- rary stoppages of the work, and for increase in bulk to reduce to scow measurement, the gross amount of matei'ial to be removed is 29,100,000 cubic yards. The material at the outer end of the channel, where the deepest cutting is to be done, consists of sand and gravel, in places mixed with mud; within the channel inside the bar it is mostly mud and sand. These characteristics of the bot tom were ascertained by soundings with the water jet, extending at several points to a depth of 40 feet below mean low water. The material to be dredged can be readily removed with suction dredges. For the past five years a suction dredge of improved type has been at work on the Mersey Bar, England, having an average working capacity of about 1,000 cubic yards per hour, including the time, occupied in transporting and unloading the dredged material. On one occasion the rate per hour has been 1,325 cubic yards. Allowing that throughout the year one third of each month, on an average, is lost by bad weather, it would require one such dredge about ten and one-half years to com- plete a 35-foot channel. This time could of course be materially reduced by using » Report for 1871, p. 110; ibid, for 1886, Appendix 13. EAST CHANNEL, NEW YORK HARBOR. 11 i more powerful dredges on the work and more of them. The prism of the northern half of the proposed channel is ahout 18 per cent smaller in cubical contents than that south of the axis. There should be no 'difficulty in opening that half of the channel for its full width of 1,000 feet and to a depth of 35 feet at mean low water within five years if a single dredge of the capacity described above is put to work therein, or, with a full force of four machiues, within one and one-quarter years. Estimate of cost of proposed new channel, 2,000 feet wide and 35 feet deep at mean low water, following the direction of the present east channel. Dredging 29,100,000 cubic yards, at 7* cents $2, 182, 500 Contingencies, 10 per cent 218, 250 Cost of four dredges, at $200,000 each 2, 400, 750 800, 000 Total 3, 200, 750 Very respectfully, your obedient servant, Lieut. Col. William Ludlow, Corps of Engineers. A. Stierle, Assistant Engineer. o Avery Architectural and Fine Arts Library- Gift of Seymour B. Durst Old York Library