S.SE. around to W., clearing Andrew's Point and Flat Ground. To the eastern entrance the course from W. around to N, NW. clear the Salvages and the reef from Straitsmouth Island. Thus we have straight courses, with no dangers--to the northern entrance, 11230 (10 points), and to the eastern entrance 674° (6 points).

The exit is equally favorable. As soon as the vessels have passed the pier-heads of the breakwater they are in the open sea. This is not the case with the interior lines. Line A has a northern entrance, with courses from S. by W. to W. by S., or 674° (6 points). Thus for this interior harbor there is a reduction in entering courses from 180° to 7830, or from 16 points to 7 points More than half the winds will be uufavorable for making the barbor. Moreover, in approaching the northern entrance with a NE. wind a mile of rocky lee shore must be passed. As for the eastern entrance, we have not only the rocky shore on the south, the narrow opening between Avery's Ledge and Straitsmouth Island must also be passed through. Unless a pier or beacon is built on Avery's Ledge this entrance will be of little practical value. Three vessels were wrecked on this ledge between September 24 and October 9 of the current year.

The northern entrance for line B is still more unsatisfactory. It is practically useless, on account of the groups of sunken ledges, known as Mitchell's, Bartlett's, and Dodge's rocks, which are directly opposite the pier-head. Even in the case of line A these rocks would be a very serious danger unless piers are erected upon them.

These considerations confirm me in the opinion that the best line for the construction of a breakwater in Sandy Bay is the line recommended in my report of November 28, 1883. To this line there are doubtless objections, the principal one being the exposure of its right wing to the violent action of the sea; but the objections to the interior lines are, in my opinion, so serious as to put them out of the question.

2. Practicability and cost of construction of a smaller harbor at the southeast point of Cape Ann.-As a basis for this investigation a detailed hydrographic survey of the area included between the Cape and Thatcher's and Milk islands has been made under my direction by Mr. Sophus Haagensen, assistant engineer. A map of this survey, showing in plan the projected breakwaters, is herewith submitted.

The breakwaters are simply enrockments of granite rubble, their crests rising to a level of 8 feet above mean high water. The inward slopes are 1 on 1, and the seaward slopes 1 on 2. This method of construction has been adopted because there is plenty of stone near at hand at Emerson's Point, and because the material can be placed in position by cars run out on the breakwater from the shore, passing over Milk and Thatcher's islands. The entrance is at the northwest corner of the harbor, between Oak's Rock and Emerson's Point. It is 1,200 feet wide. The harbor thus formed contains a high-water area of 283 acres, with an average depth of 24 feet at mean low water. Its theoretical anchorage capacity is 506 vessels.

The bottom consists of sand, cobble-stones, and bowlders, with occasionally a little clay. In some places the holding ground is good, but it is nowhere as good as in the proposed harbor at Sandy Bay.

As regards facility of entrance and departure it is evidently very defective; yet an additional entrance cannot be constructed without involving great expense in dredging and seriously reducing the anchorage capacity. There being no through current, there will doubtless be

Omitted. Printed in House Ex. Doc. No. 56, Forty-eighth Congress, second ses

trouble from ice. This harbor has land shelter from the wind through an angle of 120°. The bottom along the line of the break water, consisting of cobble-stones and bowlders resting on the underlying ledge, furnishes a good foundation.

Of these breakwaters the one connecting Thatcher's Island and Oak's Rock is most exposed to the violent action of the sea; but even this is much more favorably located as regards this point than the right wing of the original line in Sandy Bay.

The aggregate length of the line of break water is 7,545 feet. The average depth at mean low water is 17.8 feet. The cost of construction is estimated at $870,000.

3. Improvement of the harbor at Gloucester by the construction of a breakwater on the bar at its mouth. This project was examined by the late Lieutenant-Colonel Foster, Corps of Engineers, and his report thereon is given in full in the Annual Report of the Chief of Engineers for 1871, p. 869. He proposed to build a breakwater upon the summit of the ridge of Dog Bar, the eastern end being thrown back so as to connect with the shore near the quarries from which the material was to be obtained. This project was based upon surveys under Lieutenant-Colonel Foster's direction, by Messrs. H. F. Bothfeld and A. Boschké, assistant engineers.

These surveys have been employed as the principal basis of the present study. The line adopted nearly coincides with that of LieutenantColonel Foster for a distance from the shore of 1,300 feet. From this point the breakwater is carried on a straight line within Round Rock Shoal, to avoid a concave exposure to the sea.

The under-structure of the breakwater is an enrockment of granite rubble having its top at the level of mean low water. Its inward slope is 1 on 1 and its seaward slope 1 on 2. The superstructure is a granite wall with concrete filling, 10 feet wide at the top, and rising 8 feet above mean high water. The location and cross-section of the breakwater are shown on the map herewith submitted.

*

The harbor thus inclosed contains a high-water area of 1,575 acres, with an average depth at mean low water of about 26 feet. Its theoret ical anchorage capacity is 3,165 vessels, or about 0.94 that of the proposed harbor at Sandy Bay. The entrance is 2,500 feet wide. It can be safely made with winds from ESE. around to W. With winds from NNW. around to E. by N., it is difficult and at times impracticable for sailing vessels. It thus appears that the harbor cannot be safely entered when the most dangerous winds are blowing.

Near the middle of the entrance the Coast Survey chart shows a rocky shoal having over it a depth of 17 feet at mean low water. The upper part of the harbor is rendered somewhat dangerous by Ten Pound Island Ledge and the Field Rocks.

There has always been much trouble from ice in this harbor. It is feared that the construction of the breakwater will increase the difficulty, preventing the free motion of the ice out of the harbor with the ebb currents.

The harbor has land shelter from the wind through an angle of 285°. In this respect it is by far the best sheltered of all the harbors con ered.

The bottom along the line of the breakwater is coarse sand and shingle, resting upon the underlying ledge, and furnishes a good foundation.

* Omitted. Printed in House Ex. Doc. No. 56, Forty-eighth Congress, second session.

As regards the violent action of the sea, the breakwater is much more favorably situated than either of those projected for Sandy Bay. The length of the proposed line is 4,000 feet, the average depth being 17.4 feet at mean low water. The breakwater can be very conveniently constructed from the shore. Its estimated cost is $752,000.

The most serious defect of Gloucester Harbor at the present time is that it is open throughout its whole extent to the full sweep of the sea in southwest storms. This has resulted in the wreckage of many ves sels while lying in the harbor. This defect will not be fully remedied by the construction of the proposed break water. To make the shelter complete a second break water is required projecting from the west shore through Norman's Woe, as shown on the map. Such a breakwater would, however, contract the angle of entrance to the harbor, and perhaps further check the outward passage of the ice.

The line projected for this breakwater is 3,250 feet in length. The foundation is good. The proposed method of construction is the same as for the other breakwater. Its estimated cost is $607,000.

The characteristic features of the projected harbors above examined are exhibited in a condensed form in the following table, in which the data for the computation of theoretical anchorage capacity are also given. The figures relating to Provincetown Harbor are introduced for purposes of comparison:

In addition to the above investigations, which have been made in com pliance with the specific directions of the Board, I have made an examination of the area included between the Salvages, Flat Ground, and Abner's and Avery's ledges, in order to determine whether it would be practicable to construct a detached harbor at this locality. In this area eighteen borings were made. They show that the bottom consists of bowlders and solid ledge, and is unsuitable for an anchorage. This project is therefore impracticable. This investigation, although not directly mentioned in the preliminary report of the Board, was made in accordance with its wishes verbally expressed.

4. Statistics concerning wrecks.—I have made every endeavor to collect the statistics desired by the Board, but with only partial success. The

records of the Board of Trade have been carefully searched, and inqui ries have been instituted in every direction, but I have failed to find any accurate and systematic collection of statistics on this subject. The lists of wrecks submitted have been obtained by compilation, principally from the files of the Boston Daily Advertiser. They contain all the wrecks therein noted from 1874 to 1883, inclusive. It has been found impossible to obtain even an approximate estimate of the loss of life and property during this period.

The tables* submitted contain the following information:

1. The number of total and partial wrecks in each year, from 1874 to 1883 inclusive.

2. The number of total and partial wrecks in each month for the same period.

3. The number of vessels of each class totally and partially wrecked during the same period.

4. The number of total wrecks opposite certain selected localities extending along the coast from Boston to Portland, these numbers being given for each year and for the total period of ten years.

5. The number of partial wrecks opposite the same localities, and classified in the same manner.

6. The date, locality, character, and name of vessel for each total wreck.

7. The same information for each partial wreck.

8. An additional list of vessels wrecked, the character of the wrecks being unknown, compiled from the Gloucester Telegraph and News.

The chart* accompanying these tables shows graphically the number of total and partial wrecks at the various localities.

From Table I it appears that there have been averages per year of 9.8 total, and 37.4 partial wrecks; or a yearly average of wrecks, partiaand total, of 47.2.

It appears from Table II that the total number of wrecks is least during the month of July. The number gradually increases from that month until November; diminishes during December; rises to a maximum in January; diminishes again in February; increases again in March, and from that month falls off rapidly to July. The table is graphically represented by the accompanying figure. The data are not sufficiently numerous to establish any relation between the relative numbers of total and partial wrecks and the time of year.

The number and classes of vessels passing Cape Ann are contained in the appended copy of a return to the inspector of the second lighthouse district, which covers a period extending from July 1, 1880, to July 1, 1882. This return shows only the vessels passing within sight of Thatcher's Island during daylight. From this return it appears that the total number of passing vessels observed during the year ending June 30, 1881, was 37,350; and during the year ending June 30, 1882, 45,422. The number of vessels passing during the night and in thick weather cannot be estimated.

Very respectfully, your obedient servant,

Col. CHARLES E. BLUNT,

Corps of Engineers.

CHAS, W. RAYMOND,
Major of Engineers.

*Omitted. Printed in House Ex. Doc. No. 56, Forty-eighth Congress, second session.

R 10.

PRELIMINARY EXAMINATION OF HARBOR AT MARBLEHEAD, MASSACHUSETTS, FOR REPAIR OF SEA-WALL.

BOSTON, MASS., September 4, 1884. GENERAL: In compliance with instructions contained in your letter of July 31, 1884, I have the honor to submit the following report of a preliminary examination of "Marblehead Harbor, Massachusetts, for repair of sea-wall," provided for by the river and harbor act of July 5, 1884.

In compliance with instructions contained in an indorsement of the Chief of Engineers, dated March 4, 1884, upon a letter from the Hon. E. F. Stone, M. C., I examined this sea-wall, and submitted a detailed report upon the subject on April 14, 1884, to which I respectfully refer. In that report I remarked as follows:

I am of the opinion that the harbor of Marblehead is not endangered by the present condition of Marblehead Beach, and that, therefore, no action by the Government is necessary.

A second examination made personally by me, on August 27, 1884, confirms the opinion then expressed. In my judgment, "the harbor is not worthy of improvement."

Very respectfully, your obedient servant,

The CHIEF OF ENGINEERS, U. S. A.

CHAS. W. RAYMOND,
Major of Engineers.

B II.

PRELIMINARY EXAMINATION OF HARBOR AT SALEM, MASSACHUSETTS, WITH A VIEW TO BUILDING A JETTY RUNNING OUT FROM THE MAINLAND TO DEEP WATER.

BOSTON, MASS., October 7, 1884.

GENERAL: In compliance with instructions contained in your letter of July 31, 1884, I have the honor to submit the following report of a preliminary examination of the "harbor at Salem, Mass., with a view to building a jetty running out from the mainland to deep water," provided for in the river and harbor act of July 5, 1884.

The principal wharves of Salem are along the shores of South River, which constitutes the inner harbor. A channel 300 feet wide and 8 feet deep at mean low water was dredged from deep water to the entrance of this river in the years 1873-75. The project originally adopted in 1873 contemplated a construction of a sea-wall and breakwater on Long Point. This breakwater is, I presume, the jetty referred to in the act of July 5, 1884. These localities are shown in the sketch herewith respectfully transmitted.

The object of the sea wall was "to protect the remaining clay-bank of Long Point from the wash of the waves, and prevent further abrasions during east and northeast storms." The object of the breakwater was "to protect the entrance of South River from the southeast swell and partly re-establish the old natural breakwater afforded by Long Point before it was washed away."

In 1877, however, Lieutenant-Colonel Thom reported as follows:

From a recent examination of the condition of Long Point it appears that the portion of it for the protection and preservation of which a sea-wall and breakwater was