Three Hundred Things a Bright Boy Can Do

by Unknown

An insulating support must be given to the conductor, as it is to hold the accumulated electric energy, and for this the glass rod above mentioned is required. Make a suitable hole in one side of the conductor, and in it fix one end of the rod with cement. The other end can be fixed to the base-board in the same way; or a separate stand may be used; but before doing this, drive a horizontal row of strong pins along a side of the conductor, at right angles with the rod. These should be ¼ inch apart, starting and finishing ¼ inch from where the surface becomes spherical at the two ends; the heads should be cut off previously with pliers, and the external length, when driven into the wood, should not exceed ½ inch. Now erect the conductor, and see that the rod brings it level or thereabouts with the centre line of the cylinder-side. The points should not quite touch the latter; and the silk flap must not hang down far enough to come between.

There remains now but one piece of mechanism to construct—the handle. This is apt to give trouble at first, but with care may be successfully completed. A short piece of hard wood (say 2½ inches long), half of circular and half of square section, must be procured, and the rounded half cemented into one of the glass pivots. This must be done with good cement and both the glass and wood warmed, and cleaned first of all. Be careful not to crack the glass by too rapid heating. A thin layer of cement is best, while, of course, the wooden rod ought to fit closely. The square end now projecting must be provided with a handle, the making of which will serve to pass the time during which the cement is drying. Cut a square hole to fit the end in a piece of wood say ¼ inch by 2½ inches by 1 inch, which is the handle shaft. Pass a bolt through the lower part and secure the handle-bobbin itself by a nut. If nothing else can be got, a cotton-reel makes a fair handle when the flanges are cut off. If the nut works loose, pinch the threads at the end of the screw, or add a “lock nut”—i.e. an extra nut. Dry the cylinder and put a wooden stopper in the other glass pivot to keep out damp.

Take care to have the handle on the right-hand end of the machine when the rubber is closest to you and the conductor opposite; notice also that of the supports the slotted one should now be on the left-hand side.

All the woodwork, as well as the ends and pivots of the cylinder, and the glass rod should be painted with shellac varnish, which may generally be had ready mixed from paint merchants, or may be made at home by dissolving shellac in methylated spirits. A stick of red sealing-wax gives a more pleasing colour for the glass work if added to the shellac solution.

All through the construction of the machine must be borne in mind the fact that rough edges or points “attract” away the electricity, and, therefore, all the edges and corners must be well rounded off and smoothed with sandpaper, and everything must be kept clean and free from dust.

When the shellac is dry, let all the parts, especially the rubber, cylinder, and rod, have a good warming before the fire. Then fixing the cylinder in its place, press the rubber firmly against it by means of the adjusting screws. After turning for a few minutes, the handle should become stiffer, and a small spark be obtained on touching the conductor. If not, tighten up the screws a little more. It is also advisable to lay a little amalgam with tallow on the rubber, between the silk and the leather: a piece of tinfoil is also said to be of advantage when amalgam is not handy. Sometimes, too, a wire connection from the back of the cushion to a neighbouring gas or water pipe helps the success of the machine, but if proper attention be paid to warming and cleaning and the avoiding of edges and corners, success is almost certain after a short time. A delicate test is to observe whether a thread is attracted by the conductor, and if so, a spark may be soon looked for.

An iron clamp or two will be found of great assistance for holding down the base-board to the corner of a table.

The Indestructible Candles.—When a candle burns, the matter of which the candle is composed, is not lost nor destroyed. It is simply changing its form, and every part of it may be accounted for.

Fig. 1.