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34 MARINE REVIEW AND MARINE RECORD. low masts, which form ducts for the introduction of air and the expulsion of the products of combustion. As the vessel was in- tended for submarine surveying, wrecking, etc., a diver's com- partment and air lock is made a prominent feature of the design. The success of this vessel in her field has led the inventor to place on the stocks a new and larger vessel, in which it is in- tended to combine the bottom-working features of the Argonaut with the necessary properties for operation between the surface and the bottom. 'This vessel is to be fitted up with a storage battery and motor, so that communication with the surface need not be retained. The apparatus for controlling between the sur- face and bottom will consist of inclining planes fore-and-aft, termed by the inventor "hydroplanes." 'The design contemplates great stability, the intention being to maneuver on an even keel, the hydroplanes serving simply to give a vertical thrust but no turning moment about the center of gravity. At the time of writing, this vessel has not been launched, so no data is available as to the efficiency of the design, except in so far as it duplicates the Argonaut. FUTURE OF SUBMARINE TORPEDO BOAT CONSTRUCTION. Before attempting to foreshadow the future of submarine torpedo-boat construction, it will be desirable to examine in a little more detail the more important features of the modern types, as such examination, though necessarily brief, should en- able us to judge roughly both as to the propriety and possibility of future development along the present lines. Confining our- selves at present to the submersible type, we note that the French and American designs, though independently worked out are identical as to general principles and close to each other in the main features of design, the difference in the aims of the de- signers being taken into account. "The distinguishing features of submarines are, first, reserve buoyancy, and second, control in the vertical plane by rudder action only. 'The presence , of reserve buoyancy undoubtedly increases the difficulty of securing complete and satisfactory control in the vertical plane, as no matter where located it introduces an upward form which requires balancing, and it may, in addition, introduce a turning [Nov. 27. American using the light oil gasoline, with an explosive engine while the French employ a heavier oil, petroleum, and transform its energy into steam instead of using it direct in an explosive en- gine. From a purely theoretical point of view, the American system is better adapted to the purpose, involving as it does only one variable weight, fuel, against two for the other, fuel and feed water. 'lhis leads directly to simple and rapid compensating arrangements tending towards a reduction in the time necessary to pass from a cruising to the fighting condition, a tendency still further helped by the absence of the high temperature accompany- ing steam propulsicn, as well as the slow working apparatus for the escape of the products of combustion. In general simplicity and economy of space the American system offers additional ad- vantages. On the score of safety, the advantage, if any, lies at present with the French. A less volatile oil is used in the first instance, and it is probably less difficult to secure the complete expulsion of the products of combustion. The advantage, how- ever, is not important as the danger element in either case is well within permissible limits and will undoubtedly be still further re- duced in future boats employing the American system by the use of heavier oils and the perfection of the apparatus for disposing of the products of combustion. 'The principal advantage of steam propulsion lies in the fact that the designer can avail himself of very complete data based on experience, whereas since the marine oil engine of the power now required is practically new in the field, the designer is hampered by lack of reliable data. Ultimate ly, however, the oil engine will probably displace the steam engine, since the development of the former offers the possibility of a single motive power for all conditions, which will be reasonably efficient in the submerged condition. Modern chemistry is already in a fair way to provide the materials for supplying the necessary oxygen in such form as to meet the conditions imposed in a submarine. In the meantime the growing field of the oil engine, both afloat and ashore, will supply the experience nec- essary for the development of the largest powers apt to be used in the submarine. The remaining important feature common to both designs is the employment of the electric drive for submerged work. 'The Fig. 8, The Fulton A, conning tower; B, ventilator; C, gas engine; D, motor; E. steering rudder; F, diving; GG, ballast tanks; HH, trimming; II, battery; J, torpedo expulsion tube; K, propeller; L, gasoline ta k. moment about the center of gravity which also requires balanc- ing. Its advantages, however, entirely justify its presence, since it not only serves as an instantly available element of safety in an emergency, but also permits the submarine to maintain the awash condition whether underway or not, without change of ballast or direct expenditure of power. In this condition, ready to dive instantly, presenting only the conning tower as a target, and her- self commanding a complete view of the horizon, the submarine will de a great part of her work, even in the event of the perfec- tion of observation apparatus for use when submerged. It is safe to conclude then that this feature has been permanently adopted. CONTROL OF VERTICAL PLANE BY RUDDER ACTION, The second characteristic, that of control in the vertical plane by rudder action ouly, is also fully justified by tactical and construction reasons. It is obvious that a change in depth can be effected in the least time and by the least expenditure of energy, if the vessel be moved in the direction of least resistance; in other words, if she be steered up and down inclines by altering the angle of her longitudinal axis to the horizon. In order to be effective, the turning moment used must be of considerable magnitude and under the most sensitive control, conditions best met by horizontal rudders, which have also the advantages of simplicity and economy of space, weight and power. Other things being equal, the rapidity with which a submarine can rise for observation and dive again is a direct measure of its efficiency, since its chance of escape from observation or projectiles is in inverse proportion to the period of exposure. As pointed out below, a loss in this quality may be justified when balanced bv a corresponding gain in the equally important tactical feature of speed, but in no other way; hence it may fairly be concluded that this feature also has come to stay. The correspondence between the French and American de- signs extends also in a general way to the most important con- struction feature--the power plant. For submerged work both have adopted the electric drive, and for surface work and re- charging batteries, etc, both go back to the hydro-carbons, the storage battery and motor are admirable in some respects, but exceedingly inadequate in others, the principal objection being the well-known one of excessive weight and space in proportion to the power developed. When it is stated that a weight of 370 Ibs. per horse-power hour is a fair average for a suitable installa- tion, it is readily seen that there is much room for improvement. Another disadvantage of the battery lies in the care and attention necessary for its safe operation after sensible deterioration has set in. The difficulty which takes the shape of abnormal be- havior with respect to "gassing" may, under certain conditions, result in an explosion such as tock place on the Fulton last spring and more recently on the Holland. Fortunately, however, this condition is not inevitable, and is susceptible of control when it does occur. 'There is no particular quarrel with the motor, ex- cept as to the difficulty in fitting it with a suitable propeller, and the battery bids fair to develop faster in the future than in the past, on account of the increasing demand for a light, compact battery for automobile use. Its continued use may thus be ex- pected until the appearance, in practical form, of a development of a heat engine similar to that hinted at above. DIFFERENCES OF FRENCH AND AMERICAN DESIGN. The principal difference between the French and American designs lies in the cnoice made of dimensions and proportions which appears to be the direct result of different ideas as to the relative values of speed and maneuvering qualities. To attain the high surface speed desired, the French designers have: been forced to adopt a considerable displacement, great length in pro- portion to beam, the double hull with large tank capacity, and incidently the steam engine and multiple rudders. As compared with the Holland boats, the increase in surface speed is gained by a sacrifice of efficiency in three directions--first, as to simplic- ity, second as to the length of time necessary to pass from a cruis- ing to the diving condition, and third as to the necessary period of exposure for conning tower observations. No exact data is available as to the minimum observation period required by the French boats, but their extensive use of the periscope indicates a relative inferiority in this respect. In shallow water at least