EXPLANATION OF THE MACHINE.
—A Is a glass cylinder, on each end is fastened a wooden cap. One of the caps has an axis, which fits into a hole near the top of the upright piece of wood B; the other cap has also an axis, which passes through a similar hole in the upright, C, and is made square-at the end to fit the handle. B C are two upright pieces of baked wood to support the cylinder. In the upright C a small piece of the wood is cut away from the hole where the axis passes through, that the cylinder may be taken out and replaced as required; the piece of wood may be replaced and fastened by a pin running through the upright. D is an upright piece of wood, at the top of which the cushion E is attached, and is fastened to the bottom board by a sliding piece; F a screw to regulate the pressure of the cushion upon the cylinder; G a glass rod to support the prime conductor H.
The prime conductor may be made of wood neatly covered with tin foil; it is of a cylindrical form, rounded at the ends; it is fixed at the top of the glass support G, at right angles to the glass cylinder; the side of it nearest the cylinder is furnished with a row of pointed wires, to collect the electrical fluid from the cylinder. At the top of the conductor are one or two holes, that pointed wires, or wires terminated with balls, &c., may be inserted therein, which are necessary in performing experiments.
DIRECTIONS FOR MAKING A MACHINE.—The center of the cylinder, of the cushion, and of the conductor, should be of the same height. Fix the caps on the cylinder thus : Roughen with a file the glass on each end of the cylinder ; bore a small hole through the axis of that cap which does not bear the handle, then stop up the inner end of the hole with putty ; grease the outside of this cap well, put it in an upright position, and half fill it with melted cement. ii Warm well the end of the cylinder, put it into the prepared cap, and let it remain till the cement is hard, then clear out the hole through the centre by a hot wire; it will be necessary that this hole should be at all times left open, otherwise the expansion of the air by heat might' break the cylinder. The supports of the cylinder should be made of wood which has been baked in an oven five or six hours; they should be at least sixteen inches in height. The cushion may be made by laying five or six folds of flannel over the wooden back, and covered with wash leather; on the under part of the cushion sew a black silk flap, which must extend over the cylindre nearly as far as the points of the conductor.
A common glass bottle may be substituted it place of the glass cylinder, the neck of the bottle answering the purpose of an axis ; a piece of wood must be fitted very tight into the neck, and made square to receive the handle ; the hollow at the other end of the bottle must be filled with melted cement or bottle wax, and an axis must be put in and held in an upright position until the cement is hard.
* Electrical Cement — Melt one pound of resin over a slow fire add as much plaster of Paris as will sufficiently harden it, and then add about a spoonful of linseed oil stirring it well during the mixture.