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MARINE REVIEW. NE Forced Draft in Lake Steamers. The boilers of at least three lake steamers are equipped with forced draft arrangement under the Howden system. 'Two are passenger steamers, the Virginia and the Chicora, but the best example of the system for freight steamers is found in the Pioneer, built by the Detroit Dry Dock Company this spring. As a fuel saving device the owners of the Virginia speak very highly of it. That this economy can be turned to account in producing speed is proven in the Pioneer. Contracts have been practically closed for the application of the system to several lake steamers, and indications are that it will come into general use. Outside of owners who have had it applied, and engineers who have been in the boats mentioned, little or nothing is known of its workings. Fig. 3 oe L] = ! a SS. \ A Bae 5 5 { h el LL 1st i H ey JA { LL HH \ } ? 5 dy: ' it \2 +4 i Ane \ ERP P EPPO? PP PPD PP PP 29 28 Sse Bea nrg sachet lg Po 5 wi | adil unio (oe iy deer steepest (oT ee | ae | Pe ee es ras eee fp Seti ais agi 3 hee pureear a | AHO ye : : . 1 Pahl ! \ 1 | | . < The only diagrams and descriptions available show its use on the City of Paris, but there is no difference in theory and very little in its operation on lake steamers. The engraving shows the fans on deck, while on the lake vessels they are placed in the engine room. Air chambers are necessary on the City of Paris, but the volume of air required by a lake steamer can be furnished through a ventilator. 'The fans are 6 feet in diameter and are turned about 4oo revolutions by a double engine, having cylin- ders 7 by s inches. 'Ihe fans discharge downward through a square trunk, from the bottom of which an air pipe is fed down- wards and along the up-take of the boilers immediately above the top of the boiler tubes. 'The chief feature of the system 1s the series of air heating iron tubes placed vertically in the base of the uptake, the bottom tube-plate of the air-heater containing the tubes being only one or two inches above the upper row of boiler tubes. Tubes in the City of Paris are 3 inches diameter and 34 inches long. This air heater extends nearly across the whole width of the front of the boiler above the tubes. The rectangular air pipe passes along immediately in front of the air heaters and continues across the three boilers. -- There is an opening at the vertical centre line of each of the boilers to allow the forced draught to pass from the main pipe into the air heater. After passing among the tubes the heated air flows down at each side of the vuter smoke-boxes to an air reservoir which en- circles the upper half of the furnace front, occupying the whole Space upwards to the bottom of the smoke boxes. _ This air reservoir is separated from the smoke boxes by an air tight sheet iron casing. From this reservoir the air passes to the furnaces, part going into the ashpit and part into the flue above the fire, the supply to each place being regulated by separate valves. The valve for admitting the air above the fire slides on a flat plate, separating the air reservoir above from the space between the outer and inner furnace doors. These swing together on one hinge, and when the door is shut the air passes between the outer and inner furnace doors maintaining a pressure in the space as well as around the interior of the furnace front. From the pressure space between the doors the air is admitted to the furnace through a number of air distributing boxes, perforated on the side against the fire with 3¢-inch holes. These can be drilled larger or smaller according to the rate of combustion. The air passes, or is forced, onto the surface of the burning fuel. Hach ashpit has closed doors and the air pressure is also main- tained beneath the bars. The temperature of the airin the reservoir is usually about 210 degrees and the pressure of course varies. At 370 revolutions the pressure was 14% inches in the reservoir and 34 inch above the fire and in the ashpit. Illustra- tions and data are from London Engineering. Conneaut Dock Facilities. The {Pittsburgh, Shenango & Lake Erie Dock Company, Capt. H. Day, superintendent, has completed 500 feet of dock at Conneaut, O. 'There are three Brown hoists that will be in readiness for unloading vessels this week, and two Excelsior derricks are now in operation. 'The channel is 100 feet wide and there is 17 feet of water up to the docks. A light will be erected on the pier about Nov. 1. About the only inconvenience is that vessels will have to tow out stern first until the winding slip is dredged, which will be in about thirty days. 'Iwo cargoes of ore have already been ordered to Conneaut, and some coal will be shipped during the present month. A large business in ore and coal will undoubtedly be buiit up at this port next season, as the officials of the railway and dock companies are interested in coal mines at Butler, Pa., and the railway makes direct connection for Pittsburgh with the Pittsburgh & Western from Butler, Pa. The story that the harbor entrance had been filled up by a sand bar is entirely untrue. The improvements made by the new railway and dock companies include dredging to full 17 feet of water, and the projectors of the enterprise are certainly deserving of a great deal of credit for the business-like way in which they have practically opened up a new port on Lake Erie. 'Ihe last river and harbor act gave Conneaut $40,000 for improvements, but the appropriation calls for the beginning of work on new piers and an entire new channel to replace the old channel, which the dock company has improved. The people of Conneaut will make an effort at the next session of congress to have the appropriation applied toward an exten- sion of the present piers, and their request should be granted. Col. Jared Smith, United States engineer of the district, has for good reasons delayed the beginning of work on the proposed new channel, and if the change in the appropriation is made, it can be effected without loss to the government. To begin a new channel ona small appropriation, with prospects of the entire work extending over several years, would seem uselesss in the face of operations already begun for the building up of a lake business at Conneaut. Foreign and Coasting Trade. The decline of the United States merchant marine engaged in the foreign trade is brought to mind by an enquiry from Mar- quette as to the tonnage at present engaged init. For the year ending June 30, 1891, there were 1,516 United States merchant vessels of 988,719 tons engaged in the foreign trade. With the exception of two years, 1888 and 1890, this is the smallest ton- nage engaged in this trade since 1847. In 1861 it reached its climax when a vessel tonnage of 2,496,894 tons was patronized in the way of freight charges by foreign countries. From 1855 to 1860 the tonnage engaged in the coasting trade and the for- eign trade was about equal. Exclusive of small vessels and fishing craft, the tonnage engaged in the United States coasting trade is 3,529,315 tons, about four times as great as the foreign, trade tonnage. Had the foreign trade of this country grown like the coasting trade, 16,534 foreign vessels would not have brought 11,309,509 tons into the United States last year.