This dredging machine was launched on the Clyde and reached Port Said in twenty days. It measures 55 meters (180 ft. 5 in.) in length, 12.20 meters (40 ft. 1 in.) in breadth, and 3.65 meters (12 ft.) in depth. Its mean draught of water is 2.75 meters (9 ft. 21/2 in.) It is divided into eighteen watertight compartments. Five steel-pointed battering rams, each of four tons weight, are arranged in line upon each side of the chain of buckets of the dredging machine. See Figs. 1 and 2. The battering rams, suspended by chains, are raised by hydraulic power to a height varying from 1.50 to 6 meters (4 ft. 11 in. to 19 ft. 8 in.), and are then let fall upon the rock. The mechanism of the battering rams is carried by a metallic cage which can be moved forward or backward by the aid of steam as the needs of the work require. A series of five battering rams gives from 200 to 300 blows per hour. [Illustration: FIG. 1.--LONGITUDINAL SECTION.] [Illustration: FIG. 2.--PLAN] A dredging machine combined with the apparatus just described, raises the fragments of rock as they are detached from the bottom. A guide wheel is provided, which supports the chain carrying the buckets, and thus diminishes the stress upon the axles and bearings. With this guide wheel or auxiliary drum there is no difficulty in dredging to a depth of 12 meters (39 ft. 4 in.), while without this accessory it is difficult to attain a depth of 9 meters (29 ft. 6 in.) A compound engine, with four cylinders of 200 indicated horse power, drives, by means of friction gear, the chain, which carries the buckets. If the buckets happen to strike against the rock, the friction gear yields until the excess of resistance has disappeared. Fig. 3 indicates the manner in which the dredge is operated during the work. It turns alternately about two spuds which are thrust successively into the bottom and about which the dredge describes a series of arcs in a zigzag fashion. These spuds are worked by hydraulic power. A three ton hand crane is placed upon the bridge for use in making repairs to the chain which carries the buckets. A six ton steam crane is placed upon the top of the cage which supports the hydraulic apparatus for raising the battering rams, thus permitting them to be easily lifted and replaced. The dredging machine is also furnished with two screws driven by an engine of 300 indicated horse power, as well as with two independent boilers. Two independent series of pumps, with separate connections, feed the hydraulic lifting apparatus, thus permitting repairs to be made when necessary, without interrupting the work. A special machine with three cylinders drives the pumps of the condenser. An accumulator regulates the hydraulic pressure and serves to raise or lower the spuds.