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14 MARINE REVIEW. Electricity on Board Ships. _ At the last meeting of the Society of Naval Architects a paper on the "Use of Electricity on Board Ships'? was presented by Herr F. Hickenradt. In concluding a long discussion of the advantage of the electric motor and the various 'uses to which it may be applied on board ships, the author of this paper says: "With the increasing employment of electricity on ships, the question arises whether continuous or alternating currents should be chosen. In installations hitherto made the continuous current has been used; it has proved efficient, and there has been no occasion to discard it as long as there was only a question of its use in illumi- nating the interior and for search lights. The latter can only be worked with continuous currents, otherwise their lighting power would suffer a decrease of about 40 per cent. As on men-of-war the consumption of energy for the search-light reaches 20,000 to 70,000 Watts, it is evident that, for the kind of current required for lighting the interior, and for several small motors, continuous current can only be utilized. The injurious influences upon the compass may be avoided, with such a current, by careful disposition of the conduits and the scientific construction and fitting up of the dynamos. But when it comes to a general introduction of electro-motors for working the auxiliary machinery, and a central station is erected for this pur- pose, which, like one already in construction in Germany, works with a power of 300,000 volts, the employment of continuous current offers considerable difficulties. In particular, the motors placed on deck for the gun-turning apparatus and ship's winches have to be placed in such dangerous proximity to the compass, that the disturb- ing of the latter, in case of parallel current, can hardly be prevented. For the working of, this machinery the use of the alternating current becomes unavoidable, as such a current, and motors driven by it, has no influence upon the compass. This necessitates the erection of two central stations, viz., one for the search-lights and the lighting, with parallel current, and a second station, with alternating current, for driving auxiliary machinery. Unfortunately this entails the disadvantage that the motors for one station cannot be employed in ed Ts support of, and in substitution for, those of the other, and great complication would be created demanding greater capabilities from the crew. It will be impossible to avoid this if the inereased adyan- tage which the use of electrical appliances affords on board ship are to be secured. " Physical Condition of Mesabi Ores. | In his latest report to the United States Geological Survey on 'Iron Ores of the United States,"' John Birkinbine of Philadelphia says of ores from the Messabi range, Minnesota: "The objection of the physical condition of some Mesabi_ ores may be considered merely as of temporary character, and the state- ment that blast furnace managers can not use finely comminuted ores is a reflection upon the ability of men who have accomplished greater results than that of adapting their plants and their practice to the use of a deposit of such magnitude and character as has been deyel- oped on the Mesabi range. Men who have mastered the problem of producing pig iron within the narrow limits of chemical constituents acceptable to consumers, and who have reduced fuel consumption to a point approaching theoretical possibility, will find means to use liberally ore of good quality which can be supplied in quantity, what- ever its physical condition. The engineering skill which has de- signed blast furnaces to produce liberal amuonts of metal, and which are maintained in blast for long campaigns, can also perfect modifica- tions in the machinery equipment, in the method of charging, in the shape of furnace, in the gas removal appliances, or in other structural features, which will reduce to a minimum any permanent annoyances raised, that the Mesabi ores obtained such a strong footohold when their introduction was largely at a time when furnace proprietors were expending little or nothing in improvements and managers were not encouraged in experiments, but it is questionable whether this introduction was not, as a rule, at prices which left no profit for producers."' Air is Cheap--Cheaper than Dirt! FUEL IS DEAR=VERY DEAR! Six Boilers with Howden Hot Draft appliances now in Side-Weeel Steamer City of Buffalo. Dimensions of each boiler--12 ft. 6 in. diameter by 12 ft. length. HOWDEN "USE AIR AND SAVE FUEL! oe in operating expenses on Lake Ships must come from reduced coal bills. No great saving can be made in labor cost, and provisions are already low. But fuel bills can be lowered and cheap coal used to advantage by adopting Modern Methods of making steam at low cost. No manufacturer of pig iron would to-day think of running his furnace without a hot blast. Competition would not permit it. This same competition demands advanced practice in the operation of ships. The same principle is applied in the HOT DRAFT Now in use on Lake Steamers aggregating over 40,000 Horse Power. CAN BE APPLIED TO OLD SHIPS AS WELL AS NEW ONES. No complicated machinery. Cool engine rooms and cool fire holds. Estimates readily furnished for application of this draft to any steamer Dry Dock ENGINE Works, DETROIT, MICH. from comminuted ores. It is remarkable, considering the objections -- Ria arsemienes mes mee