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radiation and condensation and stand- by losses. We have therefore a sav- ing in total weights, fixed and change- able, of considerably over 300 tons) and"a saving in'fuel cost alone per trip' of about $450.00, in average good weather. There is also a further sav- ing inthe help reqtired, because, with ordinarily simple conveying and feed- ing arrangements, one man on watch would be ample tod care for the pro- ducers, the only operations to be per- formed consisting of looking after the feeding. apparatus, and about once in 12 hours to remove the accumulated ash. Cleaning fires, as with the boiler plant, is done away with, together with the heat, dust and poisonous gases attendant upon it. The saving in fuel is not alone represented by the above figures, because with the pro- ducer it is possible to use satisfac- torily grades of fuel which can not be used in the boiler furnace, as some of the poorest grades of bituminous coal have shown remarkably high effi- ciency when gasified in the producer. Anthracite or coke can be used with even better economic results than bi- tuminous coal, though for lake ships .they are probably out of the question. The stand-by losses of a steam plant are quite serious even when no steam is being used for moving ship or for other purposes. Tests of a number of installations showed an average coal consumption of 021 pounds per hour per horsepower of plant, merely - to keep up steam. Tests of an equal number of producer plants, where the consumption is merely that of a dead or dormant fire, showed 0.016 pounds per horsepower, or less than 1/10 that of thesteam plant. Of course the rea ~son is that in the gas plant, unless gas is being drawn off there is no combus- tion taking place. There are several -thousand feet of steam pipes and hot water pipes aboard the modern steamer, and even though carefully covered and protetced, the loss of heat goes on without interruption and more or less rapidly. They can not be shut off because from almost any one of them steam is likely to be demanded at any moment and must be _ pro- vided. It will probably be well at this point to give sdme description of the. pro- posed gas plant. There would be three producers of about 700 H. P. each, normal capacity; in the event of complete failure of one from any pos- sible cause the remaining two can easily take up and carry the load_be- -cause the overload capacity of a pro- -ducer is much greater than of a steam - boiler. TRE MarRINE REVIEW They. would be of the suction type, that.is to say, the type in which the air: and vapor are drawn into and through the..fuel supply by 'the' actidh of "the engine drawing! gas out, and so "in respect of all ordinary variations 'of load are automatic. The question of maintaining a supply of gas during manoeuvering, stoppage, etc.,° will be dealt with later. Of these producers there are a number of designs, but in this, as in other lines, each has its contending claims, and we will not discuss that feature; the main point is that there are a number of suction producers which are working satisfac- torily and the features peculiar to marine work can be described later at the proper point. The engine would be of the four-cylinder, double-action type, the latter feature being common to all the larger sizes for marine work, the problem of cooling the*pis- ton and rod having been satisfac- torily solved. The cylinders would be approximately 30 in. x 40° in. The engine would draw its supply of gas direct from the producer and exhaust directly into the atmosphere. It would be manoeuvered and handled with a direct reversing gear of the' same type now employed with steam, and operated by cornpressed air. An air-pump driven off the main engine, maintains an air pressure of 150 to 200 pounds -in a large air receiver which can be located anywhere most convenient. Neither reversing propel- lers or clutches of any sort will be employed. There will be two auxil- iary gas engines driving direct-con- nected generators of about 70 KW. capacity, and furnishing current for lighting and for' all auxiliaries, one set being always in reserve. A small air-pump is also driven off each of these auxiliary engines and all the air- pumps will bé automatic as in the familiar air-brake system, the idea being to' insure a constant supply of air under pressure, whether the main engines are working or not. © In handling, starting, reversing, etc, of the main engines, all the functions are performed by the air. Thus, assum- ing the engine to be at rest and it is desired to start; air is admitted to one or more cylinders and as soon as the engines have made one or two revolutions and gas drawn into the other cylinders, the air is cut off and all cylinders worked on gas if desired, or as many as be needed may be worked on gas upto full power. Simi- larly, the engine may be slowed down by cutting out cylinders, either on one or both ends at a time, stopped, re- versed, started by air and backed at 49 full power, with all the facility of the steam engine. - Indeed, in revers+ ing at fall speed the gas engine has a' substantial 'advantage over the steam engine for the reason that it is well known that to reverse the ordinary triple 'or quadruple engine under :such conditions is almost impossible, or at best extremely difficult, owing to the fact that the energy which is being imparted to the ship by the propeller - is, at the instant of reversal, transfer- red to the propeller by the ship, and, in addition to overcoming this, a cur--- rent of water must be set in motion in the opposite direction. The supply of air may be admitted. to all cylinders at once, if necessary, providing power far in excess of even the momentary reversal requirements. As some way of heating the ship must be provided for, a small boiler to furnish steam at-10 pounds'or 15 pounds pressure is installed and served by a portion. of the exhaust gases from the main engines and which are exhausted at a temperature of 350° to 450°, amply high to generate steam of even much higher pressure, and thus the heating is done absolutely without cost. It : has also been proposed to arrange this boiler to be fired with coal in case exhaust gases from the main or auxil- iary engines are not available. An ample supply of hot water for all possible purposes is available from the water-jackets of the cylinders at a temperature of about 140°, also without cost, a point that will be ap- preciated when decks are to be cleared of snow and ice and for scrubbing down in cold weather. To insure that the engines may be instantly available when manoeuvering ship there would be fitted a small ex- hauster, motor driven, which can be started at will by a switch at the handling platform, and which will maintain a flow of air and vapor through the producers with the en- gines stopped and thus insure a full supply of gas when wanted. - This ex- hauster can be allowed to run as long as the engines are being handled and shut off when convenient. The elimination of the tarry vapors before referred to, is accomplished partly by causing the tar-bearing gas- es, which are the first distilled, to pass though the hottest part of the fire, whereby they are either .con- sumed or converted into a fixed gas, and partly by the use of a centrifugal scrubber in place of the ordinary coke and excelsior scrubbers, and in which, after the gas has been intimately mixed with water in a fine spray, it is sepa- rated by centrifugal action, which