51 
down the faii'way in the hope that they may strike any 
craft which may be in the vicinity. To deal with this menace 
wherever it is suspected, countermines are exploded beneath 
the water and the concussion set up, fires, sympathetically, 
any floating mines which are near. 
Speaking of the torpedo, the lecturer pointed out that in 
its most primitive state it consisted of an explosive fired 
at the end of a long pole which projected from the bow of 
the boat. When the boat had been manoeuvred so that 
the explosive was quite close to the hull of an enemy craft, 
it was fired by means of a trigger, pulled by a rope or wire 
connection. The torpedo became the formidable weapon it 
is to-day by virtue of the addition of engines which render 
it self-propelling. The modern torpedo contains a chamber 
of compressed air to operate its engines and by their means 
it can travel at the rate of forty miles per hour, under its 
own power. The lecturer carefully explained the construc- 
tion of the war-head of the torpedo and the many intricate 
devices which render it fool-proof ; he also made clear by 
the aid of diagrams the use of the torpedo-director for accu- 
rately firing a torpedo from a moving vessel at a moving 
target. Since a single torpedo costs about nine hundred 
pounds it is desirable that, in case the mark is missed, the 
torpedo should not be liable to be picked up by the enemy 
and used against us. To obviate this a cunningly devised 
stopping gear has been arranged so that, after running a 
set distance, the torpedo shall automatically sink. 
Mr. Whyman told the story of the early submarine, 
“ David,” which was tried during the American War in 18G4. 
The “ David ” was driven by' manual power and before any 
measure of success was attained, it brought many of its own 
successive crews to their doom. By sectional diagrams, 
the internal arrangements of the modern submarine were 
explained. When running at surface level, submarines are 
propelled by oil engines, but when submerged they are driven 
by electric power supplied by accumulators. The periscope 
was described in detail, and an excellent series of slides 
illustrated the submarine in various stages of the process 
of submersion. The lecturer then spoke of the very r rapid 
development which had taken place in submarine construc- 
tion and compared the H.I., an early British submarine, 
with the later E.20. The H.I. was a vessel of 120 tons, 
developing 120 H.P., and capable of a speed of 7-| knots ; 
whereas the E.20. is a vessel of 800 tons, developing 1,600 
H.P. and capable of 20 knots. Moreover compared with the 
