The previous deductions made in this report on the rate of propagation is confirmatory of this.

A probable mean high-water line with obstructions removed is drawn on the diagram. Assuming the slope to be uniform this would increase the height of mean high-water at Pawtucket about 0.8 foot.

EXAMINATIONS OF RHODE ISLAND HARBOR COMMISSIONERS AND OF UNITED

STATES COAST SURVEY.

The Third Annual Report of the Rhode Island Harbor Commissioners contains a valuable report of examinations of the tides at Washington Bridge. Our determinations of the tides were compared with theirs; mean low-waters agree within 1 of a foot. There are two mean low-water references at India Point Railroad Bridge established by the United States Coast Survey in connection with their survey of Providence Harbor in 1874. Our determination of mean low-water is 0.091 foot above that of the Coast Survey on the Pier of India Point Bridge, and 0.171 foot above the reference on the abutment of the same bridge. The heights of these two bench-marks are given as 10.04 and 12.08, a difference of elevation of 2.04 feet; whereas the actual difference in elevation of the two points is but 1.96 foot.

VALUE OF AN IMPROVED TIDAL WAY.

On the diagram of tides there is drawn a probable line of mean high-water with tidal obstructions removed, which gives 0.8 foot additional height at Pawtucket. To secure an additional depth of this amount by the ordinary methods of dredging would cost, at 30 cents per cubic yard, $15,000; but by far the greatest benefit to be derived from clearing the tidal way at the bridges would be in the increased facilities and safety of navigating this part of the river with a slow and even flow of current.

ACTION OF THE STATE OF RHODE ISLAND REGARDING THE DESIRED

IMPROVEMENT.

A commission has lately been appointed by the State government to consider and report on the question of the improvement of the Seekonk River in the vicinity of Washington Bridge. This commission will consider the advisability of mak ing such modifications of the bridges as to secure wide draw-spans and the removal from the bottom of the river of the existing obstructions to the tide, as well as to provide for the convenience of the rail and highway traffic.

NEW OBSTRUCTIONS.

There has been some material dumped between the Twin Islands, which will, if continued, eventuate in a serious obstruction to the flow of tide. The harbor line on the west side of this part of the river has already been established, and while it embraces a large area of the tidal basin, it would not, in all probability, cause any appreciable difference in the tide, provided the east side is not ob

structed. The Twin Islands lie near the middle of the river, in the direct line between Washington and Red Bridges. The west island of the two is on the east side of the channel at the point where it makes a sharp turn. If there should be a barrier created between this island and the east shore, it would undoubtedly create a bad cross-current in the channel. The harbor line on the east side of the river here has not, to my knowledge, yet been established. It is certainly of much importance to the commerce of this river above that this line be not extended far from the shore. With wharves thrust out into the stream from both banks, a reach of river would be created that for bad currents would rival those existing at Washington Bridge. The improvement of the bridges will make pier privileges here valuable, and consequently a greater desire will be created to extend wharves into the stream.

In conclusion, I desire to recommend that the tidal determinations given in this report be adopted in preference to others previously deduced. The leveling was carefully done and checked. I have been assisted by Mr. W. H. Lawton, civil engineer, and have been kindly aided by Mr. J. Herbert Shedd, civil engi neer, chairman Harbor Commission, and Mr. Samuel M. Gray, city engineer of the city of Providence. Respectfully submitted,

H. A. BENTLEY, Assistant Engineer. Bvt. Maj. Gen. G. K. WARREN, U. S. A., Lieutenant-Colonel of Engineers.

Improvement of Providence River and Narragansett Bay, Rhode Island.

LOCALITY OF IMPROVEMENT.

Providence River is an estuary of Narragansett Bay, extending from Nayatt Point to the city of Providence. Its length is about 7 miles, with a width varying from 1,000 feet to 2 miles, and a depth in the channel varying from 12 feet to 50 feet at mean low-water, with a mean rise of tide of 4.7 feet. Near its head this estuary is joined by another, called the Seekonk or Pawtucket River, extending 5 miles farther, to the town of Pawtucket. The Providence River also contains Bulkhead Rock, for whose partial removal there is an unexpended special appropriation of $5,000. All the improvement thus far included under the title of this work is situated in the limits of Providence River, except a possible deepening upon a shoal below Nayat Point and above Rocky Point, to facilitate the navigation by means of the west entrance to the bay; it is not in the way, using the middle entrance to the bay.

HISTORY OF IMPROVEMENT PREVIOUS TO 1878.

According to the records we have, a survey was made of Providence Harbor by Lieut. Wm. S. Rosecrans, United States Engineers, under an appropriation made by the city, which was completed in March, 1853. In 1852, an appropriation of $5,000 was made, and this was expended by Capt. George Dutton, United States

Engineers, in dredging, in 1853, at the "Crook "—a bad shoal then existing just below Fox Point, and having a depth of only "4.3 feet at low-tide." The dredg ing was carried to 9 feet depth at low-water, over an area of 50 yards by 280 yards. The next appropriation was $25,000, made in 1867, based on an estimate made by an assistant of the United States Coast Survey (Mr. F. P. Webber). This was expended in 1867 by Col. D. C. Houston, United States Engineers, in dredging at the locality of the "Crook," with the exception of $2,000 employed to remove a wreck opposite Sabin's Point. With this dredging a depth of 12 feet at low-water was secured up to Fox Point.

In 1870 another appropriation of $5,000 was made by Congress, which was expended under my direction at the locality of the "Crook" (which itself may be said to have been removed), and a depth of 14 feet at mean low-water secured up to the wharves at Fox Point. (For details of foregoing, see Annual Report, 1871, pp. 727-730.)

On June 10, 1872, another appropriation was made. It was $10,000, and was all expended under my direction in widening the channel just below Fox Point. A survey was made this year, as authorized by Congress, with a view to cutting off a point of long bed," on the east side of the channel, opposite Sassafras Point. (See Annual Report for 1872, p. 820; and for 1873, pp. 968-970.)

66

On March 3, 1873, an appropriation of $10,000 was made, which was all expended in removing the point of long bed. (See Annual Report for 1874, pp. 237-239.) This practically completed the improvement by dredging as far as it was needed for the use of coasting vessels. The city also expended largely in deepening about the wharves.

HISTORY OF REMOVAL OF BULKHEAD ROCK.

An estimate for removing this so as to give a depth of 14 feet at mean low-water was made by Capt. A. H. Holgate, United States Engineers, in June, 1870, at a cost of $2,500. Its least depth then was 8 feet at mean low-water. A depth about that sought was secured that year by large blasts of gun-powder placed upon the rock.

In the Annual Report for 1875, p. 291, an estimate was submitted to increase the depth to 18 feet at mean low-water, requiring an appropriation of $5,000. This was renewed in the Annual Report for 1876, part I., pp. 207, 208; and again in the Annual Report for 1877, part I., p. 199.

On June 18, 1878, an appropriation of $5,000 was made for removing this rock, but operations upon it were reserved for the reason that the new plan requires greater depth. (Annual Report for 1878, part I., p. 232, par. 3.)

HISTORY OF THE IMPROVEMENT FOR LARGE SEA-GOING VESSELS.

This is given in detail in the Annual Report, 1878 (Part I., pp. 231-241) up to the beginning of the present fiscal year. In brief, this improvement was designed at first by the Board of Harbor Commissioners of Rhode Island, with a view to obtaining a free channel-way from Providence to the ocean, having a depth of 23 feet at mean low-water and least width of 400 feet, besides an enlarged basin for anchorage of a somewhat less depth, shoaling up to 10 feet at an extreme width

Number.

of 800 feet. This was to cost, in round numbers, $500,000. The plan was submitted to an advisory council, appointed, by request, by the President of the United States, of which Rear-Admiral Daniel Ammen was chairman. This council changed the plan somewhat, so as to make the 23-feet mean low-water channel only 150 wide, gradually shoaling to 12 feet on an extreme width of 940 feet, and to 6 feet at an extreme width of 1,060 feet; the channel way to be symmetrical in cross-section, with the greatest depth in the middle. This was also estimated to cost about $500,000. After being memorialized Congress referred the matter to the War Department for a report, which was made by myself. I submitted an estimate for work during the next fiscal year of $100,000, to make a channel 23 feet deep at mean low-water 200 feet wide, to at once open the harbor to ocean steamers to the greatest depth proposed, leaving the widening to be a subsequent matter. Congress, however, appropriated only $50,000 for this purpose. The interests of Providence, as represented by some of the most prominent public and business men, it was thought, in view of the amount appropriated, would be best served by commencing the center line of the new channel at a depth of 20 feet at mean low-water, and carrying it through between Fox Point and Field's Point to a width as great as the money would allow. This latter course was adopted by the Engineer Department.

Advertisements were issued August 5, 1878, for bids for dredging, and the work was awarded to Mr. E. R. Seward, of Albany, New York, at 114 cents per cubic yard. The work was commenced October 5, 1878, and continued up to December 25, 1878, when the contractor abandoned it. Under this contract there was removed 73,314 cubic yards of mud from the part of the river between Sassafras and Fox Points, making a depth of 20 feet at mean low-water.

WORK EXECUTED DURING THE FISCAL YEAR ENDING JUNE 30, 1880.

By act of Congress approved March 3, 1879, an appropriation of $60,000 was made for continuing this work. This money was made available July 30, 1879, and proposals for dredging under it and the money left from the appropriation of June 18, 1878 (the work having been abandoned by the contractor,) were received August 26, 1879.

The following is the abstract of proposals received:

Name and address.

Price per cubic yard.

Commence.

Complete.

The work was awarded to the Atlantic Dredging Company, the lowest bidders, and they commenced work September 26, 1879, and are prosecuting it at this date, June 30, 1880. The time of completion is December 1, 1880. The greater part of the work done has been between Field's Point and Fox Point, where a channel has been made having a least width of 200 feet and a depth of 20 feet at mean low-water. In addition to this, two cuts have been made through Pawtuxet Shoal, making a width of 70 feet and depth of 23 feet at mean lowwater. The total number of cubic yards removed, under this contract, is 327,559, all of which has been dumped in the deep water near Half Way Rock.

BULKHEAD ROCK.

This rock, as before stated, was removed to about 14 feet depth, under an appropriation of $2,500 made in 1870. The line of the east side of the proposed channel, by the new plan of improvement, extends east of the rock, and to make the required width and depth at this point requires a depth of 20 feet at mean low-water on Bulkhead Rock. Advertisements were issued for doing this under date of May 30, 1879, and the following bids were received:

Abstract of proposals received at the Engineer Office, U. S. A., June 26, 1879, at 12 m., for the removal of Bulkhead Rock, Providence River, R. I., to a depth of 20 feet at mean low-water.

The lowest bidder, Mr. D. V. Howell, having failed to furnish bonds or enter into contract, the work was, by authority from the Engineer Department, awarded to the next lowest bidder, Mr. Isaac A. Sylvester. The contractor commenced work March 8, 1880, and is still engaged on it. By the terms of contract no payment is to be made for the work until the entire rock is removed to a depthof 20 feet at mean low-water.

THE PROBABLE OPERATIONS DURING THE NEXT FISCAL YEAR

Will be the continuation of the work of dredging to a depth of 20 feet at mean low-water above Field's Point, and the completion of the removal of Bulkhead Rock to 20 feet depth at mean low-water.

The amount of money estimated necessary to complete this improvement is $330,000, of which $100,000 could be expended judiciously during the next fiscal year.

IMPORTANCE OF THE IMPROVEMENT.

Providence is a city of about 100,000 inhabitants and is the second city in size and importance in New England. It is a manufacturing city of importance.