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January, 1910 the 13 knot Laurenti boat, the actual combined brake horsepower of the engines, as shown by shop tests, was 900 instead of 750 as given. The dii- ference in speed therefore may be very largely attributed to the excess in power. .As-a matter of fact; it would be entirely possible, employ- ing the same power, to drive a suit- ably designed single hull vessel to as much as 14% knots, and it is pos- sible that this could be done with- out so great a sacrifice of submerged qualities as has been made in the case under discussion. However that may be, the point I wish to make is that the attainment of comparativety high surface speed is probably not so much dependent upon the adoption of ship-form hull as it is upon the sacrifice of the submerged speed and radius. If that be the case, it *is by state, the submarine will necessarily take on ship-form or some modifica- tion thereof. I also very much doubt whether uniformity of type is to be expected before the distant fu- ture. The various poss-ble construc- tions for submarines and their fit- tings and appliances, has been made the subject of a great many patents, and it is along the line of the most important of these patents that the various designers and. builders are de- veloping. Thus, aside from conflict- ing opinion as to the relative merits of the various systems of construc- tion, the business situation would ap- pear to operate against uniformity of design. Certainly such a result could not be attained in the near future without the formation of that mon- ster, abhorred by all good voters--a trust. Discussion by Mr. Chase. Mason S. Chase (Communicated): Important differences of opinion, ow- ing to different points. of view, will probably long continue to agitate the question of what is the best combi- nation of compromise to make in "under water torpedo boats," includ- ing armament, surface and submerged speeds and endurances, seaworthiness and habitability, also the element of "safety" or "danger" peculiar to supd- marine navigation. The many varying opinions ex- pressed are largely due to lack of any actual war experience with these ves- sels. Probably a war betwen two first-class naval powers, both provid- ed with submarines of different classes and types, is necessary to enable the services and performances of these vessels to be analyzed and compared, and to settle many mooted questions, even if not to bring about uniform- "THE MaRINE REVIEW ity of ideas. Such war experience would shed much light on the dif- ferent lines of development for sub- marine designers to follow, and, per- haps, at the same time, lead to the evolution of a new type of battle- ship which would be better protect- ed against the arms of underwater warfare than the present type of battleship is protected. We must not forget that submarines are primarily designed to fight battleships, although of course they may be called upon to engage other vessels. The Dreadnaught Type. The present type of battleship of the "Dreadnaught" or "Super-Dread- naught". class, isa vessel ot "ian speed, large endurance and heavy ar- mament, especially fitted for long range fighting and to carry on of- fensive operations at a considerable distance from its base. room, with deep water, is required to maneuver a fleet of these vessels. It is not at all probable "that tect actions between such ships, practi- cally unprotected as they are from total extinction by large explosive mines and much more vulnerable to the attacks of torpedoes than to those of artillery, will take place at the entrance of harbors, or road- steads, in the immediate vicinity of the coast. The experiences gained in the use of explosive mines in the Russo-Jap- anese war, and the facility with which mines can be laid in roadsteads and in the vicinity of harbors combined with the use which coast defense sub- marines can make of the latest im- proved automobile explosive torpe- does, as well as the more recently in- vented automobile projectile-firing tor- pedoes, all tend to restrict fleet ac- tions to the high seas. Aerial Navigation. It must be admitted that aerial crafts are now also capable of ren- dering valuable service in coast de- fense operations. We. may expect to see aerial navigation considerably modify, or even completely change methods of conducting war on both land and at sea. The recent = ad- vances in aerial navigation have been so marked, and the services which aerial craft can render in warfare as scouts and as engines of destruction, are too numerous and obvious for their possible use in warfare to be ridiculed or belittled. Both aero- planes and dirigible balloons can now travel, weather permitting, from the continent of Europe to England and return, and are already capable of Plenty of sea- - Zi rendering valuable war services in the immediate vicinity of the coast. I believe that while harbor and coast defense submarines, such as those at present in service in tue American navy, will materially aid in coast defense operations, within a limited radius, aggressive warfare against battleships, at sea, wilt have to be carried on by large sea-going submarines of high surface speed, or tactical speed, combined with large endurance, and improved habitability. Of course, with these qualities must 'be combined sufficient under-water speed and endurance. Opinions dif- fer widely as to what constitutes suf- ficient under-water speed and endur- ance. The submarines of today can best be developed into effective ones for sea-service, by holding to, or lim- iting, the submerged speed, and. in- creasing the surface speed. Increase in Displacement. Submarines of a _ displacement of over 5CO tons have already been built and some of a displacement of over 800 tons are under construction, ana a displacement of 1,000 tons is being rapidly approached. The English submarines have already attained a surface speed of 15 knots combined with a submerged speed of over 9 knots. The French boats, in ser- vice, have attained over 12 knots sur- face speed, and about 8 knots sub- merged speed. The larger French vessels, under construction, are de- 'signed for a surface speed of 15 -knots; I have not. seen any _ state- ments as to their submerged speed. | There are some elements which en- ter into what Mr. -Hay -calls the. "safety" factor which he has not men- tioned, and there are others the im- portance of which may be easily ex- aggerated. Submergence Tests. I believe that the importance of deep submergence tests is often ex- aggerated, and that the ability of one vessel to submerge deeper than an- other is only an important element of safety under exceptional circum- stances. If a vessel will always navi- gate in water of a limited depth, os say 200 ft., then there would be an excellent reason for building and test- ing her for 200 ft. submergence. If, on the other hand, greater depths are to be navigated over, and a vessel designed to submerge 200 ft. sinks in water which is 500 ft. deep, for ex- ample, the "safety" factor due to strength of hull will suddenly van- ish when 200 ft. depth is reached, and the vessel will collapse. I think