The Mechanical Handling and Storing of Material

326 THE MECHANICAL HANDLING OF MATERIAL 200 ft., must be something less at 300 ft. distance between the ships. In order, therefore, to increase the capacity of this device, it would be necessary to increase the load; but as it will be noticed that with a 200 lb. load a 1,600 lb. counterweight was employed, a 400 lb. load would require a 3,200 lb. counterweight, while a 600 lb. load would require a 4,800 lb. counterweight, and so on. The element of danger to the ship in carrying any such counterweight would seem to need consideration. If the tow-line should snap, this weight would be pulled up to the gin block, and as something would then give way, the dropping counterweight would do great damage. John E. Walsh’s Plan.—Fig. 467 illustrates a plan patented by John E. Walsh, of New York. The cable R, attached at one end to the towing boat, inclines upwards and bends over a pulley-block o, near the head of the foremast, thence bends under the pulley-block o, carrying a counterweight w. The rope is bent many times, and must therefore carry a very large counterweight to sustain the requisite tensions in the rope R. The objections which have been made to Low’s inclined cable and counterweight apply equally well to the Walsh plan. The illustration also shows overhead derricks for hoisting the load out of both hatches to platforms on the masts, the platform on the mainmast being somewhat Fig. 467. Diagram showing Walsh’s Plan for Coaling at Sea. higher than that on the foremast, and an auxiliary inclined cable between the masts adapted to carry the coal forward. Spencer Miller, the author of “Coaling Vessels at Sea,” maintains that any hoisting device of this class elevated to any height will be impracticable in a rolling sea. If the load is to be hoisted at all on ships at sea, it should certainly be steadied between guides. Lieutenant Niblack’s Paper.—Lieutenant A. P. Niblack, in a paper on “Coal Bunkers and Coaling Ships,” read before the American Society of Naval Architects and Marine Engineers in 1893, presented a most complete argument for the necessity of rapid coaling as a factor in efficiency, giving full data respecting the speed with which the ships then built in the United States could be coaled in harbour. He says : “ Our crack ship, the ‘San Francisco,’ could only take in coal at Sandy Point at the rate of 10 tons per hour, and ordinarily she takes three days, working hard, to fill up. Efficiency in ship’s crew must also be supplemented by the best mechanical arrangements practicable, and the coal must be able to go anywhere and to stay there.” Coal supply and rapid coaling are in his view most important factors in efficiency, not only in emergency, but also in times of peace, as the time spent in coating ship is time wasted. He proceeds to give figures representing the average of three or more good actual performances of each ship, and shows that the “ Chicago,” the “Charlestown,” and the