1905.] on Submarine Navigation. 161 



greater. This fact makes the adoption of higher under-water speed 

 a matter requiring very serious consideration. Some authorities, 

 who have given great attention to the construction of submarines, 

 have been opposed to the adoption of high speeds under water, because 

 of the danger that vessels when diving quickly may reach much greater 

 depths than are desirable. Causes of disturbance which might be of 

 small importance when the under-water speed is moderate, may have 

 a greatly exaggerated effect when higher speeds are reached. Cases 

 are on record where modern submarines in the hands of skilled crews 

 have accidentally reached the bottom in great depths of water, and have 

 had no easy task to regain the surface. For these reasons, it is probable 

 that while speeds at the surface will be increased, under-water speeds 

 will not grow correspondingly. Indeed, the tactics of submarines 

 hardly appear to require high speed under water, seeing that it is an 

 important element in successful attack to make the final dive at a 

 moderate distance from the enemy. It is authoritatively stated that 

 in our submarines complete control of vertical movements has been 

 secured by means of skilled operators, and that a constant but 

 moderate depth below the surface can be maintained. Proposals have 

 been made and successfully applied to small submarines for auto- 

 matically regulating the depth of submergence by apparatus similar 

 to that used in locomotive torpedoes. For the larger submarines now 

 used such automatic apparatus does not find favour, and better results 

 are obtained with trained men. 



The possibility of descending to considerable depths has to be 

 kept in view when deciding on the form and structural arrangements 

 of submarines, which may be subjected accidentally to very great ex- 

 ternal pressure. It is absolutely necessary to success that, under the 

 highest pressure likely to be endured, there shall be rigidity of form, 

 as local collapse of even a very limited amount might be accompanied 

 by a diminution in displacement that would exceed the reserve of 

 buoyancy. This condition is not difficult of fulfilment, and the ap- 

 proximately circular form usually adopted for the cross-sections of 

 submarines favours their resistance to external pressure. 



Under former conditions, there was difficulty in remaining long; 

 under water without serious inconvenience from the impurity of the 

 air. Now, by suitable arrangements and chemical appliances, a 

 supply of pure air can be obtained for considerable periods, sufficient 

 indeed for any operations hkely to be undertaken. 



The use of gasolene engines for surface propulsion has many 

 advantages. It favours increase in speed and radius of action, and 

 enables submarines to be more independent and self-supporting. 

 Storage batteries can be recharged, air compressed and other auxiliary 

 services performed independently of any "mother" ship. At the 

 same time, it is desirable to give to each group of submarines a 

 supporting ship, serving as a base and store depot, and this has been 

 arranged in this country as well as in France. With gasolene engines, 

 care must be taken to secure thorough ventilation and to avoid the 

 Vol. XYIII. (No. 99) m 



