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THE MARINE RECORD. 7 8a ee eee eee eee TS ee IN THE ENGINE ROOM. WATT’S MULTIPLE EXPANSION ENGINE. BY JOSEPH, R. OLDHAM, N. A. AND M. E At a time when the greatest crisis in the history of a free people had about reached its maturity by the sign- ing of the Declaration of Independence, another crisis was also nearing its fulfilment some three thousand miles away. Coincident with the dissipation of auto- cratic misrule forever over this country, came the dis- persion of muchignorancein connection with steam and steam engines, by the enlightened labors, if not solely by the original discoveries of James Watt; these stu- pendous events happened just about half.a century after ‘Great Newton spake and all was light.’’ The great pioneer of the steam engine was laboring assidiously to perfect the most civilizing and peace-distributing agent known either tothe arts or sciences (I hazard this opinion, notwithstanding William Ewart Gladstone’s assertion that ‘‘the violin has done more to civilize mankind than the steam engine’’), and it was in the year in which our colonists declared their independence that Watt declared the nature of his invention, in the British patent office, for utilizing steam expansively. Think of that, and then cast your retrospective mental some two years ago, _ vision upon those stupendous buildings which were in Chicago and. on which the name of Watt stood emblazoned, and consider ‘‘ What a mighty leap was that.’’? With- out the. steam engine, no such buildings could have been con- structed in ten times the period available. It appears that as early as 1776, a date well known to all. Ameri- cans, Watt made experiments on the expansion of steam, and about that time he altered an engine at the Soho works so as to test the result of an early cut- off. Six years later he took out a patent, inthe specifications of which he states that his improve- ments consist in admitting steam into the cylinders of the engine only during some part or portion of the stroke of the piston, and using the elastic forces where- with the said steam expands it- self in proceeding to occupy larger spaces, as the acting powers on the'piston through the other part or portions of the length of the stroke of the said piston. This was the first pub- lished example of the diagram of energy as applied to a steam engine. In the accompanying sketch consider the horizontal lines above and below the center line asa sectional view of the walls of a cylinder. Divide the length of the cyl- inder into, say, twenty equal parts, allowing for clear- ance. Assume that steam at the atmospheric pressure (14 pounds on the square inch) is admitted freely while the piston travels over five divisions and is then cut off. Hence, at division 10 the pressure will have fallen to % x 14, or 7 pounds. At division 15 it will be % x 14, or 4% TAMES WATT'S DIAGRAM OF ENERCY 0 1213 tm AS 6 12 se 19 20 pounds, and at division 20 it will be 4 x 14, or 3% «J pounds. Whereby it appears that only one-fourth of the steam necessary to fill the whole cylinder is em- ployed, and that the effect produced, stated briefly, is equal to more than one-half of the effect which would have been produced by one whole cylinder full of steam. The expansive principle is the same, though steam be expanded in one cylinder, as above déscribed, or in several cylinders. ih A Brown hoist would not be made any higher. by sub- stituting a six-ply rope for the single steel wire now used, nor would any absolute.gain result from the change. It is the same with the bulk of steam, the energy of which is not increased by the addition of any number of cylinders; the steam will give up the same amount of energy if expanded in one(low pressure) cyl- inder, only as it would if previously expanded by steps in several cylinders, though practical difficulties make it mecessary to subdivide the total expansion into sepa- rate stages; but this has nothing to do with the prin- ciple of expansion as delineated by Watt. Although increase in steam pressure has been the chief aid to progress in marine engineering, it is re- markable to observe how cautiously and slowly such in- crease came about. Upto the year 1850 the load on the safety valves, as a rule, did not exceed 10. pounds per square inch. Ten years later the corresponding boiler pressure was 20 pounds. In 1865 it had risen to 30 pounds. In 1872 the load on safety valves of a number of typical steamers was 5214 pounds per square inch, but in 1874 a mighty leap was taken by the late Dr. A. C. Kirk, of the firm of Robt. Napier & Sons, who de- signed the triple expansion engines of, the Propontis, BROWN CONTINUOUS ELEVATED TRAMWAY. (Courtesy of Railway Review.) which were worked by the Rowan water tube boiler, with about double the last pressure mentioned; a few years later several small steamers—notably the S. 5S. Anthracite, which was constructed under the superin- tendence of the writer—were fitted with the Perkins engines and boilers, working at about 300 pounds press- ure, but such high pressures were rapidly abandoned, and in 1891 the average was 158% pounds. Steam pressures are now rapidly increasing, and it may be that beforé many years such pressures as the Anthra- cite carried with her Perkins boiler will be the rule rather than the exception. ng eG A CONTINUOUS ELEVATED CARRIER. (ILLUSTRATED.) It sometimes happens that property with a narrow water frontage would be available for dock purposes, were such unloading machinery available as would per- mit of carrying coal, ore or other bulk freight back for a considerable distance from the water. ‘The accom- panying illustration shows the general arrangement of an apparatus of this sort, the Brown Continuous Ele- vated Tramway, which is well adapted for the purpose mentioned, and for carrying coal, ore and other ma- terials over rough or hilly country where it is imprac- ticable or too expensive to build surface railroads. Heretofore tramways for this purpose have been made of wire cable either traveling or stationary, carrying buckets secured to it or suspended from traveling car- riages, The Brown tubular tramway was designed to avoid the objections which have been encountered due to expansion and contraction of the cable, and the unreli- able supporting points of the piers, which oftén cause derailment of the carriages, on account of vertical vibration of the cable. Stationary cables, on account of the character of their surfaces, cause rapid wear of the sheaves of the carriages, and such long lines of cables as are required lead to great expense in trans- porting these outfits over rough country. ; This last objection is completely overcome by th method here shown, as this tramway is constructed in pieces which weigh from 50 pounds upward. It is con- structed of wronght iron pipes of suitable lengths for transportation, coupled together and supported upon piers in spans of 150 feet or more. The ends of the spans approaching the piers from opposite directions are coupled to a metallic supporting stand which pre- sents a curved surface at its topmost portion corre- sponding to the gradual bend of the piping. This makes the joints at the supporting piers practically a continu- ation of the exterior surfaces of the tubes themselves. The attachment of the pier leaves the stand free to swing, as the loaded carriages may in succession travel up toward and then away from it, relieving the rail and its connections at the supporting point from the twist- ing of cross strains occasioned by the passing load. The pipes between piers are connected by splicing cores that fit snugly within the bores of each of the adjacent pipes, the ends of which butt together and are securely fastened with coun- tersunk rivets. This form of construction gives strength with a smooth cylindrical track pre- senting little ‘resistance and causing little wear to the sheaves of an ordinary convey- ing machine. Safety guards are provided upon the carriers to prevent derailment. The ex- pansion or contraction is con- fined between supports: and its effect is imperceptible. The buckets are strong and light and constructed of steel with no counter-weights. It is said that this tramway can be operated upon grades steeper than can be used for wire cables, and it is always said to be economical for distances upto ten miles. This plant includes improved term- inal facilities for automatically loading and unloading the buck- ets. At the loading terminal an automatic rotary hopper is used around which the buckets pass and from which they are filled while in motion. The carriages are of mallea- ble iron with cast iron wneels properly stored to fit the pipes. The journals are of steel passed into hubs of the wheels and turn in self oiling boxes of cast iron. These boxes are made to hold sufficient wool waste and oil to dispense with the necessity of re-oiling for months. The boxes may be removed without disturbing the carriages and are made interchangeable. Precautions are taken against parts which may be jarred loose. ‘The bent part of the sus- pender rod from which the bucket bale is hung is made of malleable iron and is so constructed as to admit of easy removal of the bucket from the line by hand, and yet to prevent accidental detachment in traveling. The piers are of timber averaging about 15 feet high and varying with the profile of the ground. Spans of 200 feet to 300 feet can be used and the piers can be framed either of poles of timber stuff and should be 4x4 inches or 6x6 inches in section. The loading of the buckets can be done either at the terminal or along the line. The buckets have steel sides and flanged steel bottoms. The bale and bale-eye are one piece of malleable iron, the latches being of the same material. The terminal sheave at the upper end is provided with band brake and regulating lever to govern the speed of the tram- way when working by gravity. It may be operated by either gravity or by power. The- pulling rope is con- nected with the hanger of the carriage in such a man- ner as to dispense with side supporters or parts which would cause wear of the rope. This rope is of crucible steel wire and passes over terminal sheaves 10 feet in diameter, which are lined with maple filling pieces placed on the end of the grain. At the lower terminal an automatic dumping arrangement is provided. The capacity of the plant illustrated is from 100 to 150 tons per day of ten hours. The principal claims are simpli- city of construgtion, ease of erection, and the portable character of allits parts. These advantages are com- bined with low cost of construction, operation and main- tenance. The apparatus is manufactured in Cleveland, minimum weight, together with © -