bed rock, all requiring to be drilled and blasted before being removed. The estimated cost of this improvement is $430,625.

This work is being performed by G. H. Breymann & Bro., of Toledo, Ohio, under formal contract dated April 5, 1904, the contract prices being $3.25 per cubic yard bank measurement, for all material above the 22-foot grade, and $1.625 per cubic yard for all material removed between the 22 and 24 foot grades.

Work under this contract was commenced on July 29, 1904, continued until December 12, 1904, resumed on March 30, 1905, and continued to the end of the fiscal year. The plant used was as follows: Dredge Tipperary Boy (8 hours worked, 28 hours delayed); dredge Brian Boru (986 hours worked, 364 hours delayed); drill boat Earthquake, with four drills (2,853 hours worked); drill boat Cyclone, with two drills (3,473 hours worked); one derrick scow, with diving outfit (25 hours worked); two tugs, and the necessary dump scows.

There were removed from an area of about 23,000 square yards 13,003 cubic yards of full-rate material (above 22-foot grade), 17,578 cubic yards of half-rate material (between 22 and 24 foot grades), and 2,645 cubic yards of material for which no payment can be made (below 24-foot grade), subject to revision by future surveys, and the amount earned by the contractors was $70,824.

Over an area of about 39,000 square yards the material was broken up by drilling and blasting. The holes were generally drilled at the corners of 5-foot squares, the number of holes drilled was 17,212, being 165,011 linear feet, and 170,669 pounds of dynamite were used.

Section 4, Amherstburg reach and Hackett range. The object of this improvement is to provide a clear depth of 21 feet (at a Lake Erie stage of 570.8 feet) along Amherstburg reach and Hackett range for a maximum width of 600 feet and a minimum width of 300 feet, covering a length of channel of about 3 miles. The channel lines under this project are changed from those of former projects in order to straighten the channel, but taking advantage of former improvements. The material to be removed is limestone bed rock, loose stones and bowlders, clay, and sand. The estimated cost of this improvement is $804,000.

This work is being performed by M. Sullivan, of Detroit, Mich., under formal contract dated May 31, 1904, the contract prices being $2.40 per cubic yard, bank measurement, for material above the 22-foot grade, and $1.20 per cubic yard for material between the 22 and 24-foot grades.

Work under this contract was commenced on May 24, 1904, continued until December 12, 1904, resumed on March 21, 1905, and continued to the end of the fiscal year. The plant used was as follows: Dredges Old Glory (1,464 hours worked, 426 hours delayed), Hercules (1,756 hours worked, 649 hours delayed), Gladiator (765 hours worked, 358 hours delayed), and Tipperary Boy (1,403 hours worked, 773 hours delayed); drill boats No. 2 with three drills (4,584 hours worked), Dynamiter with three drills (4,427 hours worked), Tornado with two drills (3,650 hours worked), and Cyclone with two drills (198 hours worked); one derrick scow with diving outfit (339 hours worked), three tugs, and the necessary dump scows.

Over an area of about 120,000 square yards, the material was broken up by drilling and blasting. The number of holes drilled was 36,479 at the corners of 5-foot squares, being 260,313 linear feet, and the number of pounds of dynamite used was 328,444.

During the fiscal year there was removed from an area of about 225,000 square yards 78,260 cubic yards of full rate material (above 22-foot grade), 100,893 cubic yards of half-rate material (between 22 and 24 foot grades), and 43,482 cubic yards of material for which no payment can be made (below 24-foot grade), subject to revision by future surveys, and the amount earned by the contractor was $308,895.60. The total amount earned under this contract to the end of the fiscal year was $326,895.60.

Bar Point shoals. Between September 27, 1904, and November 22, 1904, one dredge cut was made through Bar Point shoals at the mouth of the Detroit River for the purpose of determining the nature of the material in order that it might be accurately described in specifications for future improvement. This work was performed by the Mur-O'Sullivan Dredge and Dock Company, of Port Huron, Mich., under formal contract dated September 27, 1904, for furnishing and operating a dredging plant on the basis of "time work," the contract price being $20 per hour of the actual working time.

The plant used consisted of one dredge, one tug, and the necessary dump scows, and was operated 2694 hours and delayed 309 hours. There was removed 8,226 cubic yards, scow measurement, of sand, clay, small stones, and hardpan; and the amount earned by the contractors was $5,390, being about 654 cents per cubic yard. Under date of March 2, 1905, a formal contract was entered into with G. H. Breymann & Bros., of Toledo, Ohio, for dredging at Bar Point shoals. The object of this improvement is to secure a clear depth of 21 feet (at a Lake Erie stage of 570.8 feet)

for a minimum width of 400 feet and a possible maximum width of 800 feet, covering a length of channel of about 5 miles. The material to be removed is sand, clay, silt, a few bowlders, and some hardpan. The contract price for the performance of this work is 27 cents per cubic yard, scow measurement, and the total cost will be $400,000.

Work under this contract was commenced on April 20, 1905, and continued to the end of the fiscal year. The plant used was as follows: Breymann's dredges No. 1 (380 hours worked, 283 hours delayed), and No. 2 (553 hours worked, 347 hours delayed), and Detroit Dredging Company's dredge No. 2 (517 hours worked, 264 hours delayed), three tugs, and the necessary dump scows.

There was removed from an area of about 216,000 square yards 251,674 cubic yards of sand, clay, silt, and small bowlders; and the amount earned by the contractors was $67,951.98.

Plant operated by hired labor.-During the fiscal year the plant operated by hired labor was employed as follows:

From July 1 to October 21, 1904, and from May 12 to June 30, 1905, the derrick scow with diving outfit belonging to the United States was engaged in removing bowlders from the channel at various places between the head of Ballards reef and Bar Point. The object of this improvement was to secure a clear depth of 21 feet (at a Lake Erie stage of 570.8 feet) within areas not covered by existing contracts where this could be done without dredging. During the fiscal year there was removed 660 cubic yards of bowlders from an area of about 275,000 square yards at a cost of $7,150 being $10.83 per cubic yard.

The areas improved by the derrick scow were examined by means of the sweeping raft from time to time. Also the channel from the north end of Fighting Island to Ballards reef was examined by the same means to determine what further work was necessary in order to secure the depth of water called for by the present project. This examination revealed the existence and location of a number of bowlders (with a least depth of about 20 feet) which will be removed by the derrick scow.

During April and May, 1905, an examination was made by means of the sweeping raft of the channel from Ballards reef to Bar Point, and at various other times parts of this channel were so examined. This was done for the purpose of locating and removing obstructions to navigation.

During July, August, and September, 1904, an examination was made by means of the sweeping raft of the channel to the west of Grosse Isle to determine the practicability and cost of securing a 11-foot depth through to deep water in Lake Erie for a width of 300 feet with the view to the use of such channel by light-draft vessels. It was found that in order to secure a greater depth than 9 feet (at a Lake Erie stage of 570.8 feet) dredging would be necessary, and that in order to secure that depth a stretch of channel of about 4 miles would have to be improved by the removal of bowlders overlying the bottom or partially embedded, at a cost of from $15,000 to $20,000.

During August, 1904, an examination was made by means of the sweeping raft to determine the width and location of a channel of 10 feet clear depth (at a Lake Erie stage of 570.8 feet) from the main channel at Lime Kiln Crossing to Hickory and Sugar islands, thence to deep water in Lake Erie with the view to the use of such channel by excursion steamers.

During the latter part of June, 1905, an examination was made by means of the sweeping raft to determine the width and location of a channel of 6 feet clear depth (at a Lake Erie stage of 570.8 feet) from the main channel at Ballards reef to the east shore of Grosse Isle abreast of Stony Island, thence to Hickory and Sugar islands with the view to the use of such channel by local passenger steamers. This examination has revealed the existence and location of a number of bowlders above the depth stated with a least depth of about 44 feet (present depth 6.8 feet). Two spans and the intervening pier of the railroad bridge (not in use and condemned as unsafe for traffic) between Grosse Isle and Stony Island were removed by the Michigan Central Railroad Company during April and May, 1905, in order to open up this channel.

At various times, as the progress of the work has required, stakes have been driven in the water and ranges established on shore (where practicable) for the purpose of locating and controlling dredging operations under the several contracts.

All aids to navigation have been located by transit pointings from shore stations and their positions computed.

For use in connection with the operation of the derrick scow and sweeping raft, the tug Quickstep was hired from J. H. and D. Sullivan, of Detroit, Mich., from July 1 to November 17, 1904, under emergency contract dated April 15, 1904, at $574 per calendar month; and the tug S. J. Christian was hired from G. G. and F. H. Hackett,

of Detroit, Mich., from April 24 to June 30, 1905, under emergency contract dated May 4, 1905, at $609 per calendar month.

Present condition of the channel.-As a result of all improvements, depths being referred to a Lake Erie stage of 572.6 feet above mean tide at New York, the present condition of the channel is as follows:

• From Detroit to the south end of Fighting Island there is a clear depth of 22.8 feet for a width of 600 feet or more (300 feet or more each side of the sailing lines), thence to the north end of Lime Kiln Crossing there is a clear depth of 21 feet for the same width. The full width of channel is now in use.

Along the Lime Kiln Crossing range there is a clear depth of 19 feet for the east 420 feet and 21 feet for an additional 180 feet width to the westward, with a contract in force (work in progress) providing for the widening and deepening of the west half of the channel to 22.8 feet. The east 420 feet of channel is now in use and the western portion obstructed by improvements.

Along the Bois Blanc Island range there is a clear depth of 20 feet for a width of 600 feet. The full width of channel is now in use.

Along Amherstburg reach, for a length of 2,500 feet at the north end, within the west 250 feet, there is a clear depth of 22.1 feet, and within the east part (about 200 feet width) there is a clear depth of 19.5 feet; and for the remaining part of this course (about 4,500 feet) there is a clear depth of 22.1 feet for a width of 500 feet, with a contract in force (work in progress) providing for a widening to 600 feet and deepening to 22.8 feet. The east half of the central 500 feet is now in use and the west portion of the channel obstructed by improvements.

Along Hackett range to about 14 miles south of Bois Blanc Island there is a clear depth of 19.3 feet for from 500 to 600 feet width, with a contract in force (work in progress) providing for a deepening to 22.8 feet for a width of 600 feet and length of 1,000 feet at the north end and for the west 300 feet throughout the southern portion. The east half of the channel is now in use and the west half obstructed by improvements.

From about 14 miles south of Bois Blanc Island to about 1 mile south of Bar Point there is a clear depth of 21 feet for a width of 600 feet or more; thence to Detroit River light-house, through Bar Point shoals, there is a clear depth of 20 feet for a width of 800 feet (400 feet each side of a line joining Detroit River and Bois Blanc Island light-houses). The full width of channel is now in use.

Also, at Bar Point shoals there is a contract in force (work in progress) providing for a deepenig to 22.8 feet for an additional 400 feet (or more) of width to the westward, extending from 14,000 feet north to 11,000 feet south from the Detroit River light.

Surveys. During January and February, 1905, ice surveys were made at section 2, Lime Kiln Crossing, and at section 4, Amherstburg reach, and Hackett range, covering the areas improved during the season of 1904, for the purpose of computing the amounts of material removed; at Bar Point shoals for the purpose of computing estimates for future work; and at the dumping grounds, where material was deposited during the season of 1904, for the purpose of determining their condition. These surveys consisted in the taking of soundings at 10-foot intervals along cross sections 10 feet apart, except at Bar Point shoals, where the soundings were taken at 10-foot intervals along cross sections 20 feet apart. The number of soundings taken was 91,720, at a cost of $1,620, being 1.8 cents per sounding.

Water-gauge readings.-On August 4, 1904, two temporary automatic water gauges were installed (in addition to the permanent gauge) for the purpose of obtaining data to determine the slope in the river. These gauges were all located near the Canadian shore-the permanent gauge (No. 1) being nearly abreast of the south end of Bois Blanc Island, a temporary gauge (No. 2) about 9,800 feet north of No. 1 at Lime Kiln Crossing, and a temporary gauge (No. 3) about 5,350 feet north of No. 2 at Ballard reef. These gauges were connected by a line of levels and referred to permanent bench marks on shore and all kept in operation until November 30, 1904. The records from these gauges give the following results:

Mean slope from gauge No. 1 to gauge No. 2..
Mean slope from gauge No. 2 to gauge No. 3.
Mean slope from gauge No. 1 to gauge No. 3.
Maximum slope from gauge No. 1 to gauge No. 3b.
Minimum slope from gauge No. 1 to gauge No. 3 c

"Grade to which former improvements were referred.

At a Lake Erie stage of 571.57.

At a Lake Erie stage of 574.42.

Feet.

0.45

.44

.89

1.81

.35