Perhaps this was founded upon the very ingenious probe, by means of which the great French surgeon, Nélaton, discovered the bullet in Garibaldi’s foot. He could feel something there, at the bottom of the wound; but whether it was only the bone, or a bullet embedded in it, he could not say. So he made a slender probe of rough, unglazed porcelain, and rubbed it against the hard substance. On withdrawing it, he found it marked with lead!
Still more wonderful are the medical uses of the electric light. Not only is it made to illuminate the eye to the very back, but the throat as well. A little glass-bead lamp at the end of a rod is passed into the mouth, the current turned on, and there you can see the tonsils, gullet, windpipe and all, a great deal more distinctly than the interior of St. Paul’s Cathedral on a foggy day: while, to a bystander, the patient’s cheeks and throat look as if they were made of pink glass and filled with fire inside. Further, a similar rod and bead have been actually lowered into the stomach of a very thin person, and were found to be plainly visible through the semi-transparent skin; and it is thought that this may be valuable at times in the detection of disease.
From surgery to sleight-of-hand is a long step, but we find conjurers quite as eager to avail themselves of the assistance of electricity as doctors. Robert Houdin’s book on Magic gives an account of the marvellous adaptations of this science, wherewith his private house and park were furnished. He invented many of the tricks performed with electric apparatus by his successors at the present day—not such comparatively simple ones as ‘spirit-rapping’ hammers and drums which answer questions; but clever mysteries like the iron chest which a child can lift, yet which defies the strength of a man, and the crystal cash-box. These are things which might puzzle even scientific electricians who are not in the secret. By means of the first the great wizard acquired extraordinary influence over the Arabs in Algeria, because it seemed to them that he could at pleasure take away the strongest man’s power in a moment and cause him to become as weak as a baby, restoring it again as suddenly. It depends upon the fact that a current of electricity passed through a bar of soft iron makes it into a huge magnet for the time being. The little iron box, which is to be raised or remain immovable as the conjurer wills, is placed upon a pedestal, within which is the iron bar, connected with wires to a machine outside in charge of an assistant, who, at a given signal, turns on the current.
The crystal cash-box is a casket, the top, bottom, and sides of which are made of glass, bound with wire at the edges. No deception seems possible; it is transparent right through, and is suspended over the heads of the audience by four slender wires attached to little hooks at the corners; yet several half-crowns are seen and heard to fall down inside it at the word of command.
You will naturally guess that the entire affair is under the influence of a battery ‘behind the scenes.’ The coins are first concealed within a ground-glass ornamental design in the lid, the glass of which is double. The lower slip would be just loose enough to allow them to fall, but is kept up by a bit of black thread, which rests against the wire. Just at this point the wire is made of platinum, which becomes heated by electricity much more quickly than copper or iron, being a bad conductor. Almost the instant the current passes this bit of platinum becomes red-hot, while the connecting wires are not affected; the thread is burnt through, down drops the slip of glass, and the half-crowns fall or slide out with a jingle.
We know that by the telegraph wire we can read what people write hundreds of miles away, and can hear what they say through the telephone. At the time when all these ‘phones’ and ‘graphs’ were being invented, one after another, almost daily, an American paper announced another novelty—the telegastrograph! You were to hold one end of a wire in your mouth and taste the orange, plum-pudding, or glass of wine into which the other end was stuck a thousand miles off! But although this was a hoax, it would hardly have been more wonderful, had it been true, than many real facts among the curiosities of electricity.
CHAPTER LII.—THE LEYDEN JAR, AND HOW TO MAKE IT.
Nothing can be easier than to make the Leyden jar. Procure a smooth glass bottle, that is to say an unpatterned one; and let it have a wide mouth, though this is not essential. Thoroughly clean it and dry it, and paste on to it inside and out to the height shown in the [illustration] some sheets of tinfoil. Let the tinfoil cover the glass two-thirds or what not from the base, and leave no breaks below the line.
