fall, would be very inconvenient and at times, hazardous, while it would preclude the use of the docks as winter quarters for vessels on account of the liability to dangerous movements of ice.

In view of these facts and the probable economy arising from a modification of the present plan, there is suggested a breakwater nearly parallel with the shore-line, and directly covering, from both the south and west, the area to be devoted to docks and wharves. Such a breakwater would begin on the shore-line at a point 2,100 feet south of the present docks, and pass thence on the arc of a circle of 800 feet radius to a tangent about 700 feet from the shore-line; thence northerly, and about parallel with the shore-line to a point nearly abreast of the present docks. The trace of such a breakwater would be 2,500 feet in length, and, except for a short distance near the shore end, would lie in water, about 18 feet deep at mean low water. Its distance from the shore-line would permit the docks to be extended to 10 feet depth of water, and yet leave about 400 feet between their outer ends and the inner face of the breakwater. In addition to constructional advantages, the abundance and cheapness of stone in the vicinity suggest the formation of the breakwater entirely of rubble-stone.

The position of the 300 linear feet of the present breakwater would make it serve a valuable purpose as an ice-breaker to the shore end of the suggested breakwater; the direction of the main arm would give it great stability against the movement of ice from the direction most to be feared-the southwest; while the slope of its lake face would render it quite secure against ice movement from the west. A breakwater along the lines suggested would never be subjected to the effect of destructive wave action from the south, since its main arm would be nearly parallel with the line of movement of waves from that direction, and the limited reach from the west-less than 4 miles- would preclude destructive seas from that direction.

To assist in the determination of the slopes of a random stone breakwater, the following summary of water-levels on Lake Champlain is presented: The ice in the lake usually disappears between April 1 and May 1; the highest stage of water follows the disappearance of the ice and occurs between the middle of April and the last of May; the low-water stage is reached in September and October, and from this stage to the breaking up of the ice the water slowly rises, followed by an abrupt rise in April and May. Within the last twelve years the low water has reached a stage of five-tenths foot above zero five times, and a stage of 1 foot above zero seven times. During the same interval high water has reached a stage of from 4 to 5 feet above zero six times, a stage of from 5 to 6 feet twice, and a stage of from 6 to 7 feet above zero four times. From this it may be inferred that the difference between high and low water is about 7 feet.

The following is suggested as a cross-section for a random stone breakwater: A width at extreme high water, 7 feet above zero, of 20 feet; between high water and a point 3 feet below low water a slope of 2 horizontal to 1 vertical on the lake face, and 14 horizontal to 1 vertical on the harbor face; below the plane, 3 feet below low water, the slopes to be 1 horizontal to 1 vertical on both lake and harbor faces; above the plane of extreme high water the stone to be sloped on each side so as to reach a height 3 feet at the center. By making the slopes at the beginning slightly steeper than those indicated above, the reserve material can be subsequently added to the upper parts of the work until the action of the forces impressed upon the breakwater result in such an adjustment of the material as will result in a stable equilibrium. Allowing for subsidence of 2 feet by sinking into the bottom, the volume of stone required for a breakwater on the foregoing described lines and with the cross-section stated, would be 125.000 cubic yards. It is believed that the protective posi tion of such a breakwater would permit of its construction without using stone in larger individual masses than such as could be handled with the ordinary appliances for furnishing and placing crib-filling. A part of the larger stones furnished at the quarries might without increased expense be reserved for a top covering of the upper exterior slopes of the work.

The cost of the work I would estimate as follows:

125,000 cubic yards rubble stone, at 90 cents.

Contingencies....

Total....

$112,500

17,500

130,000

The first 1,200 feet of breakwater could be built for about $55,000, and would immediately give full protection to docks built under its lee. The amount of breakwater to be built thereafter could be made dependent upon the development of the docks, and the commercial requirements of the harbor.

Very respectfully, your obedient servant,

Lieut. Col. HENRY M. ROBErt.

Corps of Engineers, U. S. A.

L. Y. SCHERMERHORN,
Assistant Engin r.

APPENDIX P P.

IMPROVEMENT OF THE HARBORS OF OAKLAND AND WILMINGTON; OF PETALUMA CREEK, AND OF THE HARBOR OF REDWOOD, CALIFORNIA.

REPORT OF LIEUTENANT-COLONEL GEORGE H. MENDELL, CORPS OF ENGINEERS, BVT. COL., U. S. A., OFFICER IN CHARGE, FOR THE FISCAL YEAR ENDING JUNE 30, 1885, WITH OTHER DOCUMENTS RELATING TO THE WORKS.

UNITED STATES ENGINEER OFFICE,
San Francisco, Cal., July 17, 1885.

SIR: I have the honor to transmit the annual reports for the year ending June 30, 1885, of the river and harbor works under my charge. Very respectfully, your obedient servant,

G. H. MENDELL, Lieut. Col., Corps of Engineers.

The CHIEF OF ENGINEERS, U. S. A.

PPI.

IMPROVEMENT OF OAKLAND HARBOR, CALIFORNIA.

The present project looks to obtaining a ship channel with 20 feet at low and 26 feet at high tide. There is now a ship-channel of 18 feet depth at high water from the bay of San Francisco to the water-front of Oakland. The corresponding original depth on the bar at the entrance was about 9 feet. The increase of depth has been secured by dredging and by the construction of two jetties extended into San Francisco Bay. The improvement of the channel has afforded much convenience to commerce, which is shown in the great increase of tonnage, elsewhere mentioned in this report.

The amount appropriated for this harbor, distributed over the years since 1874, is $874,600. The amount expended to the close of the fiscal year is $775,288.67.

THE OPERATIONS OF THE PAST YEAR.

The operations of the past year consisted in dredging a ship-channel in front of the city of Oakland 4,200 feet in length, 100 feet in width, to a depth at low water of 14 feet; in dredging the tidal basin, and in the completion of a part of the south jetty-all by contract. The first-named contract, made with Thomas H. Williams, was completed on April 7. It included 59,089 cubic yards of sand and clay, all of which was deposited on the adjacent shore by means of the hydraulic method first introduced on this work. The price paid for this work was 43 cents per cubic yard. The resistance of a part of the material approached the limit of practicability. This fact accounts for the price paid, which contrasts strongly with that of the contract of Edward G. Lukens, made October 4, 1884, for $11.95 cents per cubic yard. This contract includes about 800,000 cubic yards of mud to be placed ashore. Dredging was begun under this contract March 12, 1885, and at the close of the year 30,047 cubic yards had been excavated. The dredge was burned to the water's edge on the 19th June. Arrangements were made by the contractor under which the Von Schmidt dredge was put to work on July 1. This dredge has already proved its efficiency, so that the work will now progress more favorably. The contract work is now nearly 250,000 yards in arrears.

The contract with Edgar W. Emerson for furnishing and laying stone was completed on May 15; 16,685 tons of stone having been delivered, 101,617 square feet of facing having been laid during the year.

The stone was deposited on the south jetty, of which 2,300 linear feet were put in completed condition, with its faces laid in dry masonry. The quantity of stone required for this work exceeds the estimates, and 5,000 tons are yet required to finish the portion of the jetty laid out for completion last year, of which 818 feet remain unfinished. The method of finishing is to make the faces above low water of dry masonry, on a slope of about forty-five degrees. For this purpose large stones are used in the shape in which quarrying leaves them. They are well bonded into the wall and form a substantial finish. The land condemned for the site of the canal to connect the harbor with San Leandro Bay has come into the possession of the United States by payment into court of the sum of $39,600 appropriated by the act of July 5, 1884.

PRESENT CONDITION.

The completion of the ship-channel from the head of the jetties to Oakland wharves gives a continuous depth of 18 feet at high water from San Francisco Bay.

This depth holds only over a width of 100 feet, but there is a channel of about 14 feet depth at high water for a width of 300 feet. Depths have been maintained during the year. Near the head of the jetties and at the entrance, depth has been gained, while at an intermediate point the depth remains unchanged, the loss of about 2 feet reported last year not having been recorded. The excavation of the tidal basin during the year having been insignificant, improvement in the lower channels was not to be expected. A noticeable addition to the tidal prism

ought to be made during the coming year, now that the prospect for accomplishing dredging is good.

The exterior ends of both jetties remain in the same condition-not raised to high-water mark. No work was done on them during the past year. It is not proposed to complete them until the operations looking to a further increase of tidal prism shall have been advanced.

FUTURE OPERATIONS.

The contract with Edward G. Lukens for dredging about 800,000 cubic yards will absorb the funds now available, and no other operations are contemplated for the coming year.

The features of the work which will demand attention in the future are the continued excavation of the tidal basin; second, the excavation of the tidal canal, the land for which was acquired during the past year, and, third, the completion of 818 linear feet of the south jetty left unfin ished under the last contract.

The money next appropriated is to be applied to one or more of these objects, depending upon the amount appropriated.

The appended report of the Assistant Engineer, L. J. Le Conte, affords information in regard to the details of last year's operations and contains statistics of trade.

Oakland Harbor is in the customs district of San Francisco, at which port duties were collected during the past year to the amount of $6,610,808.

July 1, 1884, amount available....

Money statement.

Amount appropriated by act approved July 5, 1884.

July 1, 1885, amount expended during fiscal year, exclusive of outstanding liabilities July 1, 1884..

July 1, 1885, outstanding liabilities..

July 1, 1885, amount available...

$104, 238 96

7,965 48

112,204 44

91,345 85

939,929 20

Amount (estimated) required for completion of existing project..
Amount that can be profitably expended in fiscal year ending June 30, 1887 300, 000 00
Submitted in compliance with requirements of section 2 of river and
harbor acts of 1866 and 1867.

Abstract of bids for dredging channel in Oakland Harbor, California, opened March 25, 1884, by Lieut. Col. G. H. Mendell, Corps of Engineers.

Abstract of bids for dredging tidal basin in Oakland Harbor, California, opened September 23, 1884, at 12 m., by Lieut. Col. G. H. Mendell, Corps of Engineers.

Abstract of contracts made during the year for the improvement of Oakland Harbor, California.

REPORT OF MR. L. J. LE CONTE, ASSISTANT ENGINEER.

SAN FRANCISCO, CAL., June 30, 1885. SIR: I have the honor to submit the following report on the progress of operations for the improvement of Oakland Harbor during the fiscal year ending June 30, 1885. At the beginning of the year two contracts were in force-one with E. W. Emerson, for furnishing stone and placing it on the jetties in the form of dry masonry facing; the other with Thomas H. Williams, jr., for excavating a ship-channel through the hardpan shoal extending along the city front of Oakland and placing the material ashore. Both of these contracts were completed during the fiscal year.

On the 4th day of October, 18×4, a new contract was entered into with Edward G. Lukens for excavating a tidal basin in the inner harbor, the contract calling for the removal of about 800,000 cubic yards, all required to be placed ashore. This contract was in force at the close of the fiscal year.

STONE WORK ON THE JETTIES.

The contractor, E. W. Emerson, who at the beginning of the fiscal year was furnishing stone and laying it up in the form of dry masonry, met with many unforeseen and expensive delays in the form of legal injunctions. Towards the latter part of September, 1884, an injunction was served against further operations in the main quarry at Telegraph Hill. This injunction could not be removed, and as a result the delivery of small stone selected from other inferior quarries dragged along until December 16, 1884, when the contractor lost one of his barges during a storm. On the 27th of December he made application for permit to quit work until the stormy season was over. Permission was granted and the delivery of stone and dry-masonry work both came to a standstill for the time being. On the 13th of January, 1885, however, the contractor obtained substantial aid from the Kelso Quarry, Telegraph Hill, and asked permission to resume work. Accordingly, work was resumed on January 15, 1885, and continued up to May 15, 1885, when the contract requirements for delivery of stone were fulfilled.

The work of laying up the large stone in the form of dry masonry facing, however, did not reach completion until June 16, 1885.

The total amount of stone delivered during the fiscal year was 16,684.9 tons, all of which was placed on sections 1 and 2 of the south jetty.

The total amount of facing work laid during the year was 101,611 superficial feet. The present condition of the jetties is as follows:

NORTH JETTY.

This jetty was completed during previous year as far as present purposes require. No work or repairs of any kind have been done on this jetty during this fiscal year, and it may be said that it stands in substantially the same condition as existed at