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M A R I NOE R Eo oF I Eo Ne the propeller is reversed its tension upon the shaft exerts its force to hold the reversing gearing into driving contact in the desired direction. A central position of the reversing lever disengages the shaft entirely, so that the engine may continue to run idle while the propeller remains at rest. The case or drum enclosing the reversing mechanism is quite tight. The friction surfaces are metallic and are stated to be large in pro- portion to the power to be transmitted. One of the advan- tages claimed for this clutch over the ordinary toggle lever device is the fact tnat the pressure creating the friction con- stituting the driving force varies with the power required and corresponds to the thrust of the prope..er. In consequence the thrust is said to pick up its load very gradually, since the thrust of the.propeller against the friction disk comes on only after the wheel commences to turn and increases progressively until full speed is obtained. Thus the driving power of the clutch is independent of the operator. or of his manipulation of the reversing lever. This feature, it is believed, will be ap- preciated by owners of boats wherein a sudden reversing or throwing of the clutch produces an unpleasant, jerky motion. It is also to be noted that the friction clutch mechanism as a whole is extremely small and compact in comparison with the power which it transmits. It is stated-that the clutches used with various sizes of these engines 'have in all cases a driving capacity fully twice the rated power of the engines. The value of so generous a power rating for the reversing gear will be appreciated by all familiar with the service re- quired of such: mechanism and the abuses which, it must often endure. ~ LIMITATIONS OF THE SUBMARINE, Capt. Bacon, a leading authority. on submarine ohatk. in command of the British submarine fleet from its inception, re- . ferring to the fact that the form suitable for high speed on the surface is inimical to fast. steaming when. submerged,' says that the promises made by inventors and dreamers of. future potentialities are impossible of realization. It is, therefore, important to make a compromise, as great speed on the sur- face involves size, and this militates against rapid sub- mergence, and also increases the vulnerability, not only be- cause of the greater target but also of the tardy disappearance. Guns to face torpedo boat destroyers on the surface might be carried, but the difficulty is to know how they could be dis- posed of when submerged. Moreover, speed under water in- volves great weight for accumulators, which must be costly in ~ upkeep, because they could not last more than five years. Capt. Bacon says that all difficulties of stability and regulation of submergence have been overcome, and as regards safety gear suggested says that the idea of fitting bulkheads has been rejected, because of the psychical characteristics of sailors, who in the hour of danger would not, care to be isolated from their fellows in very confined 'spaces. Moreover, the smallest fractures when the vessel is under the surface might mean the inrush of water at the rate of four tons in 10 seconds. Auto- matic gear for causing the boat to rise at once to the sur- face is not to be encouraged. He prefers to depend on the brains of the men, and that has proved effective in the emer- gencies that have so far arisen. Sir William White deprecates high speed when submerged, as a slight inaccuracy in the angle of the boat would take her to dangerous depths in a much shorter period of time--a matter of which he has had experience, as years ago he was down in a submarine boat which was raised with extreme difficulty. TRADE NOTES. The residence which Louis C. Tiffany, vice president of Tif- fany & Co., is building at Cold Spring Harbor, N. Y., will be equipped throughout with H. W. Johns-Manville Co.'s Noark fuses and also with their 85 per cent magnesia pipe covering. The Baltimore Gas Machinery Co., 14 West Lexington street Baltimore, Md., has issued a catalogue devoted to section gas producers. The catalogue gives a very exhaustive description of the producer, together with costs in comparison with other fuels. It will be sent to any one for the asking. The Durable Wire Rope Co., Boston, Mass., have installed in Machinery building, Block 34, at the St. Louis®Exposition, a full line of samples of their wire rope. They have also a rope drive in operation. The company states that they will be glad to meet there any one interested and furnish complete in- formation regarding the various uses to which their wire Fone may be applied. The National Electric Co. of Milwaukee has just issued a catalogue devoted to stationary and portable motor-driven air compressors for continuous and-intermittent service. The bulletin, which is No. 350, is very beautifully illustrated and gives a thorough® description of these compressors, together with their dimensions and capacities. It will be sent to any: one upon request. The Thomas H, Dallet Co., Philadelphia, have just issued a catalogue describing their portable drilling machinery. The Dallet Co.. was established in 1883 and has been continually engaged in the building of portable machinery since that time. The usefulness of their machines has been tested in thousands of ships. The catalogue goes very completely into the drills made by this company and may be had upon request. An elaborate catalogue of over 300 pages, has recently been' issued by the Star Brass Mfg. Co., Boston, Mass. This annual: catalogue, considerably enlarged because of addition of new devices, illustrates and describes the steam engineering spe- cialties of this company, among which may be mentioned its lines of vacuum, pressure and water gages, "pop" safety, globe, angle and relief valves, revolution counters, lubricators whistles, clocks, etc. That the goods of this company are in the front rank, is attested by their wide use on battleships, cruisers, and torpedo boats built by the United States govern- ment, as well as on transatlantic, lake and coasting steamers. _ The De Beers Mines Co., Ltd., Kimberly, South Africa, has cabled an order for a third Westinghouse-Parsons steam tur- bine generating outfit of 1,500 kw. capacity for their power plant at Kimberly. The new turbine unit will be similar in every respect to the two which have been in operation for somewhat' over a year. That a concern with the standing of the De Beers company should install machinery built at such a distance speaks well for the confidence which they place in it. The new turbine unit will operate at 150 lbs. boiler pressure; 35° :superheat and' about-.23. in yacuum. Taking into account the altitude of Kimberly, this would be equivalent to about 27 in.*vacuum at sea level. The new unit will be shipped via New York in about six months. The powerful new dredge Hercules, owned by Michael Sullivan of Detroit was completed July 13, and in tow of one of Hackett's tugs was towed to the lower Detroit river near Amherstburg, where it will immediately start on a part of the government contract for deepening and widening the Amherst- burg reach and Hackett range channels. The Hercules is equipped with a six-yard hard rock dipper dredge and is de- signed to perform the heaviest kind of work. The, dredge is 110 ft. long, 4o ft. beam and 12 ft. deep, and has the most modern machinery and equipment available. All engines, hoisting and anchor machinery are independent. The plant in- cludes an electric light engine, The new four-masted schooner Wm. J. Quillan was launched from the New England Co.'s yard, Bath, Me., July 12. < The new five-masted Sohoouer Margaret Haskell will be launched at Camden, Me., July 16. .