1046 THE COLLIERY GUARDIAN May 24, 1918. done as perfectly as it is really possible to do it, the result is perhaps as good as the spelter method. On the other hand, if the end be bent back and secured by clips or clamps to the rope, the result will not be so good; but since clip and clamp methods are easy, they will continue to be popular. Moreover, even with such devices there is sometimes a right and a wrong way. Some devices of this character have a broad, smooth surface which bears against the one part of the rope and a thin or narrow ring surface which bears against the other part of the rope. In such cases the broad, smooth surface should bear against the main rope, and the sharp ring against the short end piece of rope. In this way the crimping of wires on which the direct strain comes is avoided. The mechanical devices used to handle the clam- shell bucket are several in number, the simple derrick being a very advantageous one for this purpose. There are two forms of simple derrick, the guyed derrick and the stiff-leg derrick (see figs. 2 and 3). In both there is a vertical mast of wood or of steel with a pivot or foot resting in a socket. It may be held in the upright position by wire rope guys, or by two wooden or steel struts forming the stiff legs. In either case the mast may be turned on its vertical axis. The boom is a long piece of wood or steel which has one end pivoted at or near the' base of the mast in such a way that the outer end of the boom may be raised and lowered. Sometimes a single casting is used to support the foot of the mast and the pivoted end of Fig. 3.—Stiff Leg Derrick. the boom. In such cases this casting will properly have a protuberance or pivot underneath resting in a cup, though sometimes there is a separate casting for the boom set up a foot or so on the mast if desired. When the mast is rotated, the boom swings round simultaneously, and vice versa. This possibility of rotating the whole derrick, taken in connection with the fact that the outer end of the boom may be drawn in towards the mast or allowed to drop away from it, and also the fact that the load suspended from the boom may be lifted and lowered without disturbing the boom, makes the derrick very useful in unloading coal from cars and barges. The derrick will be set up where the boom can be swung round, and then set so that its far end will be over the car or nearly so. It will at the same time be located so that the boom end may be swung round sufficiently to enable the bucket to be discharged at the point desired. Of course, there should be a hoisting engine to handle the various ropes, in addition to the two ropes running to the bucket, as has already been described. A third rope secured to the outer end of the boom runs to the head of the mast and thence more or less directly to the hoisting engine. This rope lifts and lowers the boom. If a bull wheel is employed as a means of rotating the whole derrick, there will be a rope round this wheel managed by the engine; or if the derrick has only to be rotated at rare intervals, this may be accomplished by one or more men, with the assistance of a lever. The hoisting engine will therefore have three or four drums or other- means for handling the various ropes, each rope having to be controlled quite independently of the others. This combination of hoisting engine and derrick is probably one of the most economical possible,. considering the range of operations performed. As to choosing be- tween a guyed derrick and a stiff-leg apparatus, it may be pointed out that the choice is determined by the conditions themselves. If a swing round in a full circle is required, an ordinary stiff-leg derrick is out of the question, the usual utmost swing with such a machine being three-quarters of a circle, or a little more, but not nearly a full circle. A guyed derrick will enable a complete circle to be made, provided there is space for the guys. An ideal arrangement would be to use flat guys and distribute them at equal intervals all round. In many cases, however, suitable points of attachment are not avail- able for the bottom ends of the guys, and frequently the guys have to be arranged steep. If the boom, when in vertical position, is too long to clear the guy ropes, then it will be necessary to give up swinging round a full circle, or else the boom will have to be shortened. With a boom not too long a full circle may be made, but the*boom will require hauling up. This is a little complicated, perhaps, but the men on hoisting engines generally get fairly expert. In setting up a guyed derrick a good deal of attention should be paid to the guys and their anchorages at the ground level. Ordinarily it will be well to space the guys at equal intervals, and all at the same angle with the horizontal. The ropes should be generous in strength, and should be galvanised. As these ropes do not have any motion over sheaves or the like, a 6-strand rope with seven wires in a strand is just the thing. Turnbuckles should be arranged, one in or at one end of each guy. It is then possible to put all the guys under the same strain and to loosen and tighten them as time goes on and conditions change. As to strength, it has already been mentioned that steepness of a guy effects a depreciation; and, indeed, a guy rope set up at 60 degrees with the hori- zontal is only one-half as strong as the same guy arranged perfectly horizontal, it being understood that the pressure against the mast is exerted hori- zontally. The anchorages should be very firm, and, especially prepared, may advantageously be con- structed of concrete. A steel rod with an eye in the end, this eye projecting from the anchor block, will be a suitable device for providing a point of attach- ment for the guy or its turnbuckle. The steel rod will, of course, be buried in the concrete, and should form part of a network or its equivalent, the whole being embedded in the mass of the block and consti- tuting a kind of reinforcement binding the concrete into a strong unit. An ordinary derrick has one disadvantage, which sometimes will have to be taken into account, namely, that it is immovable. In a great many cases movability will not be needed, as a good derrick will be able, when advantageously placed, to reach and unload several cars without requiring any one of them to be shifted. Where it is desirable to move the unloading appa- ratus up and down alongside a line of cars, a locomotive crane (fig. 4) is an efficient unloader. Such a crane, if of the revolving variety, can do just about all that a derrick could do, and in addition can shift its position up and down a special track. The clam-shell bucket is again the proper thing to use for the purpose of actually getting the coal. No doubt more attention is required than with a derrick, lest the swinging of the loaded boom should result in Fig. 4.—Locomotive Crane. overturning the whole. The locomotive crane may operate on an elevated track laid on a trestle. A convenient arrangement is where the railway siding is on one side of the trestle and the storage space on the other. At Detroit, Michigan, the Murphy Power Company uses a locomotive crane and a trestle. At Decatur, Illinois, the A. E. Staley Manu- facturing Company employs a 15-ton locomotive crane, which is mounted on the equivalent of a railway flat car. Consequently this crane can operate on the railway track itself—for example, by coming up behind a car and working from this position. The Fort Worth Light, Heat and Power Company, at Fort Worth, Texas, uses a locomotive crane in con- nection with an elevated structure. The cars run in alongside the boiler house. Between the track and the house a steel skeleton deck is located at the level of the roof. This deck is supported along one side by the boiler house wall, and along the other side by steel uprights. A track is laid which has a width about the same as the deck, and a 4-wheel flat car carrying the rotatable crane runs along this track. The coal is lifted by the grab bucket attached to the crane and discharged into the longitudinal bunker above and between two rows of boilers. At the League Island Navy Yard, Philadelphia, the Navy employs a locomotive crane precisely after the manner of a power-rotated derrick, the superstructure of a loco- motive crane being set up on a fixed pier of steel construction. The location is alongside a wharf, so that the crane takes coal by grab bucket from barges and discharges into a hopper serving a conveyor. The Michigan Power Company at Lansing, Michigan, employs a locomotive crane operating on a track at the general level to take coal and delivei' it to elevated bins through hatches in the power house roof. The transfer here is substantially the same as that at Fort Worth, but is accomplished differently, as might be surmised from the fact that the one crane operates at the ground level, while the other does so at an elevated level. At Lansing the long boom is lifted until its outer end is above the hatch level. There is a difference in duty, however, inasmuch as the Fort Worth crane delivers not to the side of the roof, but well over towards or at the middle. The grab bucket is often suspended from a trolley (fig. 5), which may run on a track or rail arranged on a bridge or on a bridge and cantilever. The bridge or the cantilever may extend over one or several rail- road tracks, or the cantilever may reach out over a barge berth. The Cleveland Electric Illuminating Company employs a bridge, with cantilever at one end, commanding two or more railway tracks. The grab bucket digs the coal from the cars and delivers to storage. The New York Edison Company has a big storage yard at Shady Side, on the west bank of the Hudson. Barges are unloaded by a bucket suspended from a trolley running back and forth on a bridge and cantilever projection. It is frequently unnecessary for the trolley to wait until the loaded grab bucket has been lifted the full distance. The trolley may start in advance, and this is also the case when a derrick or locomotive crane is used. . Some- times there is no need for the swing or the lift of the boom to wait for the bucket hoisting rope to finish its lift, though, naturally, more or less skill is required when a combination of two movements is made. At Camden, N.J., the McAndrews and Forbes Company use a locomotive crane which, mounted on a 4-wheel truck, digs coal from barges that come up to the wharf. The Berlin Mills at Berlin, N.H., use a big locomotive crane for getting coal from railway cars and delivering it to points fairly distant, either vertically or horizontally. The boom being 55 feet long has a wide reach, and travels on a special track having an 87 in. gauge. Such a wide gauge track may at times be arranged to include the railway track between its rails, as is the case at Berlin. Even this boom can hardly compare with a crane in use by the Duquesne Light Company of Pittsburg, operating a 5-yard bucket on a 110-ft. radius. The Michigan Alkali Company at Wyandotte, Mich., uses, in con- nection with a circular storage system, a big crane to take the coal from railway cars. The crane has a radius of 80 feet and uses a 2-ton bucket, and runs on a double track, the gauge being 20 feet. The North-western Iron Company, Mayville, Wis., uses a crane with a 100-ft. radius, running on a double track of 20-ft. gauge. I he car dumper does not seem to have been in- stalled by consumers as part of their equipment for quick discharge of coal from railway cars. As some of the large power companies are burning a tre- mendous tonnage, this fact may sooner or later impel them to turn to the car dumpers as a solution of the unloading problem. There may also perhaps be other consumers whose conditions may make the car dumper a suitable and economical apparatus. Several types of American car dumper have already been described in our columns.* Similar to the derrick is the mast and gaff (fig. 6). Even with a derrick it is not necessary to step the boom at the foot of the mast. With the mast and gaff arrangement, however, the “ boom ” may be stepped up as high as the middle of the mast. The arrangement is, moreover, different in other respects. For instance, the mast is not, or need not be, arranged to turn, and the same applies to raising and lowering the gaff. On the other hand, the gaff may be set to swing through a horizontal arc without any change in the elevation of its upper end. Ropes running from the mast head to the gaff head hold the gaff in position. The grab bucket is suspended from a rope passing over a wheel hung from the gaff head. A good example of this type of apparatus is an installation * Colliery Guardian, June 16, 1916, p. 1133; August 4, 1916, p. 207; March 9, 1917, p. 483 ; August 31, 1917, p. 397.