If the construction of the instrument just described appears too formidable a task to my young readers, perhaps they may yet be inclined to experiment with
Take a lacquered iron “tea-tray;” cut a sheet of stout brown paper so as to fit the flat part of the tray, and fix two strips of paper at each end by means of sealing-wax. These strips serve as handles by which to lift the paper, and the sealing-wax, being a non-conductor, prevents the electricity from passing off. The tray is also insulated by placing it upon two tumblers.
The sheet of paper is now heated quite hot, placed on a wooden table, and rubbed with a hard and very dry clothes-brush. Then it is lifted and placed on the tray.
The paper is negatively electrified; it induces a similar state in the lower side of the tray, which should be touched a moment with the finger; then lift the paper from the tray. An electric spark can now be taken from the latter.
The strips by which the paper is lifted can be brought together, and held by the thumb and finger of one hand, leaving the other free to take the spark. The paper may now be replaced. By touching the lower surface of the tray, and lifting the paper as before, another spark may be obtained, and so on for several times, if the air be dry.
This piece of apparatus, also called Pfeiffer’s electrophorus, is composed of a thin sheet of ebonite, measuring about six by eight inches. A small sheet of brass, about five by three inches, is fixed on one side. With this, electricity may be evoked with unusual readiness.
It is placed flat on a wooden table, and rubbed successively on both sides with the open hand; if lifted in the left hand, and the right hand is presented to the brass, a spark will be received.
This may be made as follows: Fill a plain glass tumbler two-thirds full of shot; insert the bowl of a spoon in the shot, leaving the handle projecting. Hold the tumbler in the hand, and bring the handle of the spoon near to the electrophorus—previously prepared for action—so as to receive its spark. On repeating this a few times, the electric fluid will be accumulated in the “jar,” and the many small sparks may be obtained as one large one, by approaching the finger to the spoon, still holding the tumbler in the other hand.