The mention of armor plates inevitably brings to our minds the
consideration of ordnance, but I do not intend to say even a few words
on this head of invention and improvement--a topic to which a whole
evening might well be devoted--because only three years ago my
talented predecessor in this chair, Sir William Armstrong, made it the
subject of his inaugural address, and dealt with it in so masterly
and exhaustive a style as to render it absolutely impossible for me
to usefully add anything to his remarks. I cannot, however, leave this
branch of the subject without mentioning, not a piece of ordnance, but
a small arm, invented since the date of Sir William's address. I mean
the Maxim machine gun. This is not only one of the latest, but is
certainly one of the most ingenious pieces of mechanism that has been
devised. The single barrel fires the Martini-Henry ammunition; the
cartridges are placed in loops upon a belt, and when this belt is
introduced to the gun, and some five or six cartridges have been drawn
in by as many reciprocations of a handle, the gun is ready to commence
firing. After the first shot, which must be fired by the pulling of
a trigger in the ordinary way, the gun will automatically continue
to send out shot after shot, until the whole of the cartridges on the
belt are exhausted; and if care is taken before this happens to link
on to the tail of the first belt the head of a second one, and another
belt to this, and so on, the firing will be automatically continuous,
and at a rate anywhere between one shot per minute and six hundred
shots per minute, dependent on the will of the person in charge of the
gun, the whole of the operations of loading, firing, and ejecting the
cartridge being performed by the energy of the recoil. This perfectly
automatic action enables the man who works the gun to devote his whole
attention to directing it, and as it is carried on a pivot and can
be elevated and depressed, he can, while the gun is firing, aim the
bullets to any point he may choose.
Since 1862 the power of defending seaports has been added to by the
application of submarine mines, arranged to be fired by impact alone,
or to be fired on impact when (under electrical control) the firing
arrangement is set for the purpose, or to be fired electrically from
the shore by two persons stationed on cross-bearings, both of whom
must concur in the act of explosion. These mines are charged with
gun-cotton, the development of which owes so much to Sir Frederick
Abel, while for purposes of attack the same material, not yet in
practical use for shells, is taken as the charge for torpedoes, which
are either affixed to a spar or are carried in the head of a submerged
cigar-shaped body. By a compressed air or by a direct steam impulse
arrangement these weapons are started on their course and are
directed, and then the running is taken up by their own engines
operating on screw propellers, driven by a magazine of compressed
air contained in the body of the torpedo. Means are also provided to
maintain the designed level below the water surface. The torpedo may
either be projected from the war ship itself or from one of those
launches which owe their origin to our member, Mr. John Isaac
Thornycroft, who first demonstrated the feasibility of that which was
previously considered to be impossible, viz., the obtaining a speed
of twenty miles and over from a vessel not more than 80 feet long.
Experiments have been carried on in the United States by Captain
Ericsson to dispense with the internal machinery of the torpedo, and
to rely for its traverse through the water upon the original impulse
given to it by a breech-loading gun, carried at the requisite depth
below the water level in a torpedo boat. This gun, having a feeble
charge of powder at a low gravimetric density, fires the torpedo, and,
it is said, succeeds in sending it many yards, and with a sufficient
terminal velocity to explode the charge by impact. Also, in the United
States, experiments have been made with a compressed air gun of
40 feet in length and 4 inches in diameter (probably by this time
replaced by a gun of 8 inches in diameter), to propel a dart through
the air, in the front of which dart there is a metallic chamber
containing dynamite. Although no doubt the best engineer is the man
who does good work with bad materials, yet I presume we should not
recommend any member of our profession to select unsuitable materials
with the object of showing how skillfully he can employ them. On
the contrary, an engineer shows his ability by the choice of those
materials which are the very best for his purpose, having regard,
however, to the relative facilities of carriage, to the power of
supply in sufficiently large quantities, to the ease with which they
can be worked up or built in, and to the cost.