274 POPULAR SCIENCE MONTHLY 



questionable that improvements in or alternatives to internal combus- 

 tion engines will favor the increase of power in relation to weight, and 

 so will tend to the production of vessels of higher speed. The com- 

 paratively slow speed of existing submarines as compared with destroy- 

 ers and torpedo-boats of ordinary types admittedly involves serious 

 limitations in their chances of successful attack on vessels under way, 

 and higher surface speeds are desirable. 



Concurrently with the construction of submarines, experiments 

 have been made in this country and abroad to discover the best means 

 of defence against this method of attack. Here again authentic details 

 are necessarily wanting, since the various naval authorities naturally 

 wish to keep discoveries to themselves. It is very probable, however, 

 thai published accounts of tests between swift destroyers, vedette boats 

 and submarines are not altogether inaccurate, and according to these 

 accounts the periscopes of submarines have been found useful by assail- 

 ants as the means of determining the position of the submarines, and 

 aiding their entanglement. Comparatively limited structural damage 

 to a submarine in the diving condition may be accompanied by an 

 inflow of water in a short period, which will result in the loss of the 

 vessel. The accident to Submarine A 1, which was struck by a pass- 

 ing mail steamer, illustrates this danger. It is reasonable to accept 

 the published reports that large charges of high explosives exploded at 

 a moderate distance may have a serious effect against submarines, and 

 cause them to founder. Their small reserve of buoyancy in the diving 

 condition makes them specially liable to risks of foundering rapidly, 

 and little more than a crevice may practically fill the interior with 

 water in a very short time when the vessel is submerged even to a 

 moderate depth. On the other hand, reports which have appeared of 

 the manoeuvres in France and elsewhere, when attacks have been made 

 li\ submarines on vessels at anchor or under way, show a considerable 

 percentage of successes. Such exercises are valuable no doubt for pur- 

 poses of training, but under peace conditions it is necessary to avoid 

 the risks of damage to submarines, which might easily become serious 

 if the defence were pressed home as it would be in war. When the 

 officers and crews of submarines know that they will be treated more 

 considerately than in real warfare, they will naturally take chances, and 

 make attacks involving possible destruction under the conditions of a 

 real action. In short, naval manoeuvres in this department, while they 

 may be useful in increasing the skill and confidence of officers and 

 men in the management of submarines, can be no real test of fighting 

 efficiency. 



Submarines and airships have certain points of resemblance, and 

 proposals have been made repeatedly to associate the two types, or to 

 use airships as a means of protection from submarine attacks. One 

 French inventor seriously suggested that a captive balloon attached to 



