at the edge, and a very large mass of dirt lies near the top of the sea wall, exposed to be washed into the Harbor by the next heavy sea from the East rising above the sea wall, which is a frequent occurrence.

A larger slide than this has taken place on the Northeast point of the Island. In the course of a year part of this loose material will be washed away and deposited in the Harbor.

This represents the average yearly process of the destruction of the Island, and its injurious effects upon the Harbor have been stated already in general by the U. S. Commission. The final result of the present examination of the outer Harbor will be shown in figures when the report of the U. S. Commission is made, and by comparison with former surveys the amount of deposits in the principal channels created by the waste of the Islands.

Allow me to mention one striking feature of these deposits. The stone beacon on Great Brewster spit was built at the extremity of the spit. In 1856, the spit had grown from the waste of the Great Brewster so much toward the main ship channel, that it became necessary to erect a lighthouse on its new extremity. A portion of the Great Brewster was about that time protected by a sea wall, but the greater part of the Island remained unprotected from want of means to complete the work, and the waste of the Island has been allowed to continue. To-day the point of the spit projects two hundred feet further into the main ship channel since the spit lighthouse has been built.

The keeper of this light, Mr. N. R. Hooper, who lives on the Great Brewster, has made some interesting observations since 1849, showing the immediate connection between the waste of the Great Brewster and the growth of the spit, by yearly recorded measurements of the waste of the Island and the growth of the spit.

Only an effectual and complete protection of the Islands by sea walls and grading of the bluffs will prevent their gradual

destruction, and the consequent filling up and formation of obstructions in the main ship channels.

My examination leads to the following recommendations, which I hereby respectfully submit.

The present sea wall on the Great Brewster will require for a distance of nine hundred feet to be raised about four feet in height. At this increased height the sea wall should be continued around the Northeast Point of the Island, in a curve for five hundred feet, thence on the Northwest and West side of the Island about one thousand feet. A wall of ten feet high will be sufficient.

On the South head of the Island the present sea wall should be continued for three hundred and twenty feet.

The North and West side of Gallop's Island is also gradually but continually wasting, and the material from its high banks goes directly into the Channel called the Narrows, and furnishes also the material for the growth of Lovell's Island, encroaching upon this most important channel.

Since last fall large masses of dirt have fallen from the banks and lie exposed to the wash by the waves in a Northeast storm. A sea wall of one thousand seven hundred feet in length and of ten feet in height, is a great necessity.

Also the repairs of the sea wall on Deer Island should be made during this summer. About four hundred feet of the wall are in danger of being precipitated by the next severe Northeast storm, the dirt filling behind the wall has been washed out and the deck stones have caved in. Ballast filling is re quired, and replacing of the deck stones.

Besides the building of these sea walls it is of the greatest importance to grade all the bluffs to a slope of sixty degrees, and where admissible to forty-five degrees. The slope to be seeded down with a suitable grass. The spray, rain, and frost will otherwise continue its destructive effects, and slides from the bluffs will send dirt to the top of the sea wall where it will lie exposed to be washed into the Harbor.

From detailed estimates the sum required to build the above

recommended sea walls, and for grading the bluffs, amounts to

$ 149,770.

I have the honor to remain,

Most respectfully,

Your obd❜t servant,

A. BOSCHKE,

Engineer U. S. Harbor Commission.

HIRAM A. STEVENS, ESQ.

Chairman of Joint Committee on Boston Harbor.