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8 MARINE REVIEW. Docks of Ohio Coal Co., Duluth. Improvements in coal docks at upper-lake ports can hardly be said to have kept pace with the car dumping machines of shipping porfs on Lake Erie, but a considerable amount of new construction work has been going on of late at the head of the lakes, and some of tlre docks of Duluth, Superior and Ashland are now capable of handling immense quantities of coal. Among the best of these docks is that of the Ohio Coal Co. at Du- luth, opposite the entrance to the harbor and east of Garfield street. This dock is a sand-filled structure 1,560 feet in length by 300 feet in width, on which both hard and soft coal are handled. 'While the arrangement of most docks in the neighborhood permits of the mooring and unloading of coal-laden vessels on one side of the dock only, the Ohio Coal Co.'s dock Fig. 2 shows these improved trusses and towers. The square movable towers under the water-front end of the trusses are so designed that they can be changed later on into a stationary trestle, requiring, the placing of the moving and hoisting machinery to either side of the pyramidal por- tion of the towers; for this purpose it is intended to place a running track on the plate girders forming the tops of the square towers. This change is calculated to greatly increase the storage capacity of the dock, but it is not contemplated for the present. During this year four new steel con- veying trusses with movable towers were erected, with enlarged extension booms somewhat different in design from those built in 1895, as will be seen in Figs. 3 and 4. Power is,supplied from a central steam plant of five 100 horse power boilers burning anthracite dust, the steam being conveyed on each side of Fic. 1. OHIO COAL COMPANY'S DOCK AT DULUTH. has two water fronts available for this purpose. The dock is symmetri- cally arranged, with double railroad tracks running through its center. These tracks are straddled by a high trestle, on top of which rest two single-rail tracks, on which are run the large conveyor trusses. The water- front ends of the trusses rest on movable towers. Along one side of the trestle supporting the conveyor trusses is arranged a shed 950 by 150 feet covered by a water-tight roof for the storage of anthracite coal, all of which is kept under shelter. Fig. 1 is an illustration representing the dock from the storage shed side, showing the conveyor trusses from which coal is dumped into the shed by temporarily removing a section of the roof underneath: When the dock through 8-inch steam mains, protected by Harvey's patent wooden jackets, which reduce the condensation to a minimum. At inter- vals of about 200 feet along the pipe line it is provided with expansion joints and drip traps to carry off the condensation. The pipe has 125 openings, permitting the making of connection at almost any point where it is necessary to place the hoisting rig. The hoisting from vessels and stock piles is done by means of double-drum engines with steel Boge car- riages and Newell & Ladd self-filling clam-shell buckets. The equipment of ten derricks gives an average daily capacity of 4,000 tons, in unloading vessels, and a like amount in loading cars. This latter work is done by means of pockets along the railroad track in the center of the dock, from Fia@. 2, 1895 CONSTRUCTION.--CONVEYOR TRUSSES. FIG. 8, 1897 CONSTRUCTION. the dock was originally built in 1883 structures similar to those shown in the accompanying illustrations, constructed of timber throughout, were provided. These structures were designed for smaller buckets than those In use at present, which had to be loaded by hand. In 1895 the old wooden conveying trusses had become worn to such an extent that either extensive tepairs or renewal became imperative. It was therefore decided to prac- tically reconstruct the trusses, trestle and towers of steel adapted to heavy self-filling, clam-shell buckets, and also to equip the towers with new hoisting machinery operated from a new stationary steam plant. Six new trusses with extension booms overhanging the vessels, and three 90- foot sections of trestle over the central tracks were erected; new machinery was provided for ten sets of conveyors and a steam plant for twelve sets, and the large covered shed for storing anthracite coal was built. . The steel sections of the central trestle rest on pile and concrete foundations. which the coal goes over chute screens into the cars. The screenings' are handled by the Jeffrey conveyor and revolving screen and are thus separated into the different sizes. The structural work in 1895 was furnished by the Lassig Bridge & Iron Works of Chicago, and erected by Messrs. Kelly & Atkinson "of the same city; that of the present year was furnished and erected by the J. G. Wagner Bridge Works of Milwaukee. The steam plant was fur- nished in 1895 by Messrs. Robinson & Cary, of St. Paul. The entire superstructure is of reamed soft steel, designed by K. E. Hilgard, con- sulting engineer of St. Paul, late engineer of bridges for the Northern Pacific 'Railway; he also had general supervision of its manufacture 2nd erection. The main trusses, about 146 feet in length, weigh twenty tons each and the lower square movable towers ten tons each. A complete conveyor, including the 46-foot extension boom, upper pyramidal tower,