APPENDIX No. 2. Vol. iv., p. 69.

Dredging Machines of the River Clyde Trust, with their Dimensions, Cost, and Power.

The plant is made up as follows:—

6	steam dredgers,
14	steam hopper barges,
1	steam tug,
3	diving bells,
270	punts, and numerous small boats.

The value of the whole plant is estimated at 140,000l.

General Dimensions of Largest Dredger:—

	Ft.	In.
Extreme length	161	0
Depth at sides amidships	10	0
Breadth moulded	29	0
Rise of deck at centre	0	10
Sheer of deck	2	3
One bucket ladder, 89 ft. 6 in. between centres.
Size of buckets, 3 ft. 3 in. ⨉ 2 ft. 5 in. ⨉ 1 ft. 11 in.
Capacity of buckets, 13½ cubic ft. each.
Mean working draught, 6 ft. to 7 ft.

Engines.—Horizontal, condensing, 2 cylinders with link motion, governor, and all recent improvements, say 75 H.P.

	Ft.	In.
Diameter of cylinders	2	3
Length of stroke	3	0

Average strokes per minute, 33.

Boiler.—Horizontal, tubular, with 3 furnaces, each 3 ft. 1½ in. wide.

	Ft.	In.
Length at bottom	9	4
Width	11	4
Height	13	10
Working pressure of steam, 10 lbs. to 15 lbs. per square inch.

Consumption of coals, &c.:—

Coals, per day of 10 hours	50 cwts. to 60 cwts.
Tallow, per day of 10 hours	about 1 lb.
Oil (lard), per day of 10 hours	13½ gills.
Waste, per day of 10 hours	1½ lb.

Nos. 11, 12, 13, and 14. Steam Hopper Barges.

General dimensions:—

	Ft.	In.
Length of keel and fore rake	145	0
Breadth, moulded	25	0
Depth, moulded	11	9
Length of hopper	56	0
Breadth of hopper at deck	19	6
Breadth of hopper at bottom	8	6
Height of coamings at sides of hopper	1	4

Capacity of hopper, about 320 cubic yards, or 400 tons.

Engines, &c.—Direct acting, condensing, 2 cylinders, each 24 in. diameter and 24 in. stroke. Expansion valves, link motion, &c., say 40 H.P.

Propeller, 3 bladed, 8 ft. diameter, pitch about 16 ft.

Boiler.—Cylindrical, 11 ft. diameter, and 9 ft. 6 in. long, tubular, fitted with superheater, 2 furnaces, working pressure, 30 lbs. per square inch.

Draught, speed, &c.—Loaded, with sand, 9 ft. 6 in. forward, and 11 ft. 6 in. aft. Light, boiler full, and 20 tons to 30 tons of coal in bunkers, 4 ft. forward, and 8 ft. 2 in. aft.

Speed, 8 miles to 9 miles per hour.
Strokes of engine, average 70 per minute.
Steam pressure, 25 lbs., vacuum, 24.

Consumption of coals, &c.:—

Coals, per day of 10 hours	70 cwts.
Tallow, per day of 10 hours	5 lbs.
Oil, per day of 10 hours	20 gills.
Waste, per day of 10 hours	2 lbs.

“The cost of dredging, of course, varies much according to the character of the material to be lifted, and to the power of the dredger employed and the capacity of its buckets. The material to be dredged ranges from silt and sewage deposit to the hardest of gravel and boulders, completely concreted together. Where good lifting sand was being dredged, one of the two most powerful of the dredgers lifted, on each of five consecutive days, 2240 cubic yards, or about 2800 tons; the engine working 9 hours the first day, 9¾ hours the second, third, and fifth days, and 9¼ hours the fourth day; the average strokes of the engine being 33 per minute, and the average depth of water that the points of the buckets were working at, 20 ft.”