Now let the handle of the switch be moved to the other terminal, as shown by the dotted lines. The current will now go from the right-hand end of the battery to press and center of switch as before, it then goes down the arm of the switch up to the trumpet by the wire on the left side, and down to the other end of the battery by the wire on the right side, as shown by the arrows. Therefore when the arm of the switch is at A C the press will work the drum; when it is at A G the press will work the trumpet.
Suppose we have no press, but instead of it we have only one wire going straight from the right-hand end of the battery to the middle of the switch. Now let two incandescent lamps be substituted for the trumpet and drum. When the arm of the switch is at A C the current goes straight up from the right-hand pole of the battery to the center of the switch, along the arm, up to the lamp on the left-hand side, and down to the other pole of the battery. Now, suppose the arm of the switch is moved to A G, the current will go up as before to the center of the switch, down by the arm, up the wire to the lamp on the right-hand side, and back to the battery by the other wire. In the first case, therefore, the lamp at D lights up, in the second case the lamp at T lights up. The wires from C to D and G to T may be as long as you please, you can therefore control the lamps when they are far apart or in different parts of the house. When the arm of the switch is central neither lamp lights up, or, if you are fitting up the trumpet and drum, the press will not work either when the switch is in this position. This is an advantage, as when people get too inquisitive you can turn off the current, and then whatever they do they will not make the trumpet or drum work till you turn it on again, which you can do when you want them to work for you!
The construction of the switch is so simple that it is hardly necessary to explain the method of joining the wires, but I may say that one is to be joined to the bottom of the brass pillar in the center which supports the brass arm. The others are joined to the right and left terminals, generally by brass screws under the base, but sometimes by screw terminals at the upper surface; this depends on the make of switch which is purchased.
Ingenious readers can easily make a switch for themselves; it only requires a brass arm attached at one end to a central figure, and long enough to touch two screws, or pieces of brass, fixed to the base on opposite sides of it, when turned in their direction. The end of the arm not supported by the brass pillar is provided with a small wooden handle to turn it by.
The switch should be arranged to occupy some dark corner in which you can turn on drum or trumpet to work from the “presses” at will without any one seeing you alter it.
I will only add one thing in conclusion, and that is, that you can have the double wire from the battery and center of switch to the press at the end as long as you like, and it can turn about behind furniture or under the carpet as much as you like, and it will still work instantly from the end press.
Now, by scraping the wire clean at any intermediate point, or as many points as you like, and arranging a simple spring contact fastened to the wires without breaking them so that they can be made to touch when required and spring apart directly the touch is removed (this is easily done with two springs consisting of two strips of sheet brass, one fastened to one wire and one to the other, separated by a piece of wood except at the end when pressed together), you can make the trumpet squeak or the drum roll at any part of the room you like. The springs can be hidden under the carpet so as to be absolutely undiscernible except to the initiated. The best places are under furniture with rather long legs; the foot of the operator can then be placed on the springs, and so make them meet and the trumpet or drum sound without the least chance of detection. The wires not being broken in fixing the springs as described, those springs which are closer to the battery, in no way interfere with those which are further off, as, when these are used, the current simply runs round those that intervene between them and the battery, without being in any way hindered in its course, and the press at the end of the double wire will, therefore, work just as if no intermediate springs existed.
[Simple Electrical Experiments.]
Frictional electricity is pre-eminently a winter amusement. Not that it is not equally possible to produce the same result in summer, but then other occupations are forced upon us, while in the long winter evenings, with a good fire to dry the air of the sitting-room, the conditions are particularly favorable to electrical phenomena. If a hard frost sets in the conditions will be still more favorable, as this dries the air and the ground outside, while on a wet evening a large fire and warmer room will be needed to produce as good results.