Fig. 6.—Hook From Which to Suspend the Magic Drum.
W, Double wire from battery and “press.” B, Beam of wood from which drum is suspended. H H, Brass hooks at side. S, Ebonite or sealing-wax between the hooks. The beam is, of course, shown in section.
Now you can pull back the wire and fix the hook firmly in the hole, hiding the double wire at the top of the beam (of course if it is high up no one will be able to see over the top of the beam, so you will be quite safe); the hook being thus fixed will not attract any one’s notice, and look quite unsuspicious. The chief glory of the double hook thus constructed is, of course, that you can remove the drum whenever you choose, for examination, and whenever you hang it up you have only to hitch one eye over one side of the hook and the other over the other side, and the drum will work. People who are not up in the matter cannot conceive how the electricity can get to the drum, when it is simply hung by an (apparently) ordinary cord and ordinary eyes to what looks like an ordinary hook attached to a beam in a plain and straightforward manner.
You are now possessed of an electric trumpet and an electric drum, which you can put one at one end of the room and the other at the other. By running double wires from battery and press to the trumpet, and another double wire from battery and press to the drum, you can arrange matters so that when you put one press down the trumpet works, and when the other press is put down the drum works. If you want to work both together you must either have a very powerful battery (say 6 or 7 cells, No. 2 Lechlanche) or two batteries, one for trumpet and one for drum. If you want to use one battery for both you can make either work (at different times) from the same battery and presses, wherever they may be, by having a two-way switch in a dark corner of the wire.
Fig. 7.—Method of Joining Switch Drum and Trumpet to Press and Battery.
S, Switch. B, Battery. P, Press. D, Drum. T, Trumpet. The arrows show the course of the current when the switch is at A C and A G respectively.
It is very confusing business setting up the wires so as to produce the right effect, which is to change the current from drum to trumpet and vice versa in a moment by merely altering the handle of the switch. Readers who are not accustomed to the work will find it most intricate, and as I have done it myself several times, they may as well have the benefit of my trouble. I therefore give an illustration of how to connect up the wires (Fig. 7), and hope it will make matters clear to them. An explanation of the picture is necessary.
Suppose first of all that the switch is at A C, then the current will travel from the right-hand end of the battery, B, up one wire of the double conductor to the press, P, as shown by the lower arrow, through the press and along the wire, as shown by the top arrow, to the middle of the switch, A, down the arm of the switch to C, up one wire of the double conductor to the drum, and down by the other wire to the other end of the battery.