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HOWDKN HOT The foregoing letter tells the results of the system in the City of Alpena and City of Mackinac. The Howden system is adapted to use of anthracite, slack, or other inferior quality of coal, which cannot be burned with natural draft. Mr. Howden has booked orders during 1893 for its application, under royalties, to 52 steamships, mostly of large size, including the large passenger steamers now building at Philadelphia for the American Line by Wm. Cramp & Sons. The aggregate power of these 52 steamships is 145,600 I. H. P. The new steamer Gothic, just completed for the White Star Line by Harland & Wolff, Limited, Belfast, is fitted with Howden's system of hot draft. She is the largest steamer that ever entered the port of London, with the exception of the Great Eastern. This system is also being fitted to the two Cunard Company's twin screw steamers. It is now in order to show the features of the system that produces such results. The economic generation of power by modern high pressure compound marine engines, has resulted mainly from improvements in the engines, themselves, little being effected by the boilers. Of late, however, considerable attention has been given to boilers, resulting in various systems ot forced draft, mechanical stoking, etc. Most of these schemes are designed to increase the power of the boilers, rather than their efficiency; in fact the general result is a loss of economy. Forced draft (so called) schemes may be divided into two systems: The oldest, by induction, effected by a tall stack, steam jets or a fan exhauster in the stack. The other system produces a pressure of air in the ash pit under the grates, either by a SYSTEM. 67 closed stoke hold, into which the air is forced by a fan blower, or by forcing the air directly into closed ash pits. In all the above systems, the.air for combustion is supplied at the natural temperature, cold. The Howden system supplies hot air to closed ash pits, resulting in the production of maximum power together with the highest efficiency and economy of fuel. The means by which these objects are attained is by first placing an air-tight reservoir or chamber on the front end of the boiler and surrounding the furnaces. This reservoir, which projects from 8 to 10 inches from the end of the boiler, receives the air under pressure, which is passed by the valves into the ash pits and over the fires in proportions exactly suited to the kind of fuel used and the rate of combustion required. The air used above the fires is admitted by its valve to a space between the outer and inner furnace doors, which swing on one hinge, the inner being the proper door of the furnace, having perforations and an air-distributing box through which the air under pressure passes into the furnace and over the surface of the fuel. The The outer or air tight door is not exposed to the heat of the furnace, and simply retains the air under pressure entering from the upper valve. The air from this valve, besides filling the space between the doors and passing into the furnace through the inner door, also fills the spaces above the dead-plate around the furnace door, and passes into fixed air-distributing boxes covering the whole surface inside the furnace. In this manner the furnace front castings arc preserved from the injurious effects of the great heat of the furnace, while the air entering under pressure is highly heated before being distributed in small jets or streams