In an age of technological marvels, how best to arm his navy was a question which was readily answered for the gentlemen of 1886. With its engine powered by compressed air achieving an impressive 24 knots over 600 yards, and delivering a payload charge of up to 100lb of gun-cotton, the Whitehead torpedo was clearly the weapon of choice. The Whitehead's accuracy and unwavering course were thanks to an ingenious mechanism in the 'balance-chamber' ('C' in the accompanying diagram) which operated self-correcting fins at the tail. Britannica's author observed that the device "has never been patented, but is a secret ; the details of it, however, have been purchased by all prominent maritime nations."
Less prominent maritime nations may have had to settle for the Sims or the Brennan.
"The Sims torpedo is cigar-shaped, and is suspended to a boat-shaped float. The torpedo is propelled by screws driven by an electric motor situated in the body, the current for which is supplied from a dynamo ashore. The electric cable is coiled on a drum in the torpedo, and pays out as the torpedo advances. The torpedo is also steered from the shore by an electric current. Its speed is about 12 knots."
I'm sorry, an electric torpedo that plugs into a generator on land seems a little impractical? Well, how about this then :
"The principle of the Brennan torpedo is as follows. The torpedo contains two drums upon which a large amount of pianoforte wire is wound. One end of the wire from each drum is taken to large drums ashore, which are revolved by a steam-engine. By winding up on the large drums ashore a rotatory motion is imparted to the drums in the torpedo, which by means of gearing revolve two screw propellers, and these drive the torpedo through the water. The torpedo ca be steered from the shore in any direction, by winding on one drum faster than the other, which alteration in motion moves a vertical rudder on the torpedo."
Although it sounds more like something Heath Robinson may have thought up, impeccable online sources inform me that the Brennan was, in fact, the War Office's defensive weapon of choice at ports harbours throughout the British Empire from 1886 to 1905. The invention of Australian Louis Brennan, it was "the world's first guided weapon," and the only surviving example of this historic weapon can be admired at the Royal Engineers Museum in Kent.
The full article TORPEDO by Commander Edwin J. P. Gallwey of the H.M.S. "Polyphemus" can be read at www.1902encyclopaedia.com. Reading it will at the very least give some indication why the thickness of ironclad armour was of such national importance, and along with articles such as vol. 9's FORTIFICATION, it ominously foreshadows the industrialized carnage and horror of the First World War.