138 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE [VOL. XI. 
because its speed under water is so slow relative to that of the battle- 
ship. The detection of a submerged boat is, however, a difficult matter, 
the only visible point being the head of the periscope, which needs to be 
shown above the surface only from time to time. In still water the 
periscope is fairly visible by the wake which it makes on the surface 
when emerging, but in rough and misty weather it is extremely difficult 
to detect. Detection from air-craft is under certain circumstances 
fairly easy and this mode seems to promise a great deal. When the 
periscope is discovered, it will be at once subject to a hail of projectiles 
from light guns, and if it is hit the boat will be blind and helpless. If, 
after that, the boat shows its conning tower above the surface, it will 
generally be exposed to destruction by artillery fire. 
Seaplanes or other types of air-craft may possibly become a dangerous 
enemy of the submarine boat not only in helping to detect it but also 
by direct attack with bombs. When the boat is submerged it is quite 
helpless against bomb dropping. Even very light bombs are likely to 
prove destructive, and since the air-craft is in no danger of counter- 
attack from the submarine boat, it can go very low and hitting should 
not be a difficult matter. The submarine boat cannot even observe 
a seaplane when immediately over it. A further development of the 
seaplane is, therefore, likely to prove extremely dangerous to the sub- 
marine boat. Numerous small patrol-boats properly equipped for 
attacking the submarines with gun, ram and other weapons are likely to 
prove effective in the vicinity of the coasts. 
While the active or offensive means of defence are in this case as 
elsewhere the most effective, the battleship possesses means of defence 
of a passive nature such as watertight subdivision, elastic bulkheads 
and underwater armour, which may be still further developed, but 
experiments and war experience are required to throw light on the 
problems involved. The superior speed of battleships is of course in ~ 
itself a means of protection. On account of the present limited range 
of submarine boats and perhaps especially on account of the limit to 
the endurance of the personnel, they do not render the powerfully armed 
and well protected artillery ships superfluous. Large seagoing battle- 
ships and battle cruisers are yet required in order to control the ocean, 
but as matters stand now, the smaller enclosed seas such as the Baltic, 
the North Sea, the Mediterranean, the Yellow Sea and other similar 
waters may be practically controlled by submarines and by light, fast 
vessels. In the presence of an active enemy well provided with sub- 
marine boats large vessels cannot operate in such seas except under 
the greatest precautions, going at high speed and using all possible 
means of defence. 
