Steampunk Prime_ A Vintage Steampunk Reader - Mike Ashley [73]
For foggy weather signaling there is still another ingenious device. A circular hole, about two feet in diameter, is cut in the vessel below the water-line, and closed by a circular steel plate or diaphragm one-eighth of an inch thick. On the inner side of this there is a thick iron chamber, completely inclosing the space behind the diaphragm; and here is placed a small, shrill, steam whistle, worked by compressed air or steam, and controllable by a valve or key. Alongside of this apparatus is another diaphragm made like the first; but there extends from the centre of it a very short fine steel wire, highly stretched, the other end of which is connected to a sensitive diaphragm, from which tubes lead to both ears of the signalman. By an adjustable attachment this steel wire can be regulated to greater or less tension, as a violin string is, and it is tuned to respond to the note given out by the whistles on other steamers, which are all of precisely the same pitch. In fogs the signalman alternately sounds the whistle and listens for a return, his receiving apparatus not being responsive to any other sound than that to which it is tuned, beyond the rippling or dashing of water on the sides of the vessel and the movement of the propelling shutter machinery, which are continuous and do not interfere with the signalman’s hearing a periodic musical sound. The sound-waves of the whistles are communicated to the water by the steel diaphragm in front, and travel through the sea just as in air, but much farther, since the conductivity of water for sound is greater than that of air. One of the most important uses of this machine on large passenger ships is to ascertain the direction of approaching vessels with exactness, and for this purpose they have two sets of diaphragms on opposite sides of the ship, connected telephonically.
Still another contrivance for preventing collisions or giving notice of the nearness of icebergs or derelicts impressed me. This is “the automatic pilot,” a small cigar-shaped copper vessel some fifteen feet long and twenty-four inches at its greatest diameter, having within it an electric motor that drives a screw propeller at its end. From the masthead a reel passes two insulated wires, which run from the ship’s dynamo electric engine, down to the cigar-shaped “pilot,” to which they are joined side by side, about two feet apart. They not only carry electricity to the motor of the pilot, but also cause the pilot to move in harmony with the steamer’s course. As soon as the fog appears the “pilot” is launched, and the current passing to it through the wires from the masthead, revolves the motor in the little pilot-craft and sends her shooting ahead of the ship or steamer. If the pilot tends to veer from a straight line one of the wires becomes more taut than the other, and so affecting the steering apparatus as to bring the copper boat back to the right course. I forgot to say that these wires or cables, although having only about the thickness of a knitting-needle, are twisted together from a number of very fine steel wires: and as the speed of the pilot is greater than the ship’s and keeps her about half a mile ahead of the latter, the wires always tend to become taut. If the pilot strikes any obstacle the fact becomes known at once to the man at the dynamo, and the engine is stopped and reversed without loss of time. Many serious accidents have been avoided by this precaution. The automatic pilot-boat is taken on board again, of course, when the fog clears.
It will be evident to anyone who reads this little sketch of my first experiences and impressions that, with such means of cloud-flashes and sea-signalling-besides which, it must be mentioned, the construction of ocean cables was now very cheap