. The science-history of the universe . es diameter onthe mouth of a clean, dry glass bottle. By a fine silkenthread from the ceiling, right over the mouth of the bottle,suspend a small cork ball, about the bigness of a marble;the thread of such a length as that the cork ball may restagainst the side of the shot. Electrify the shot, and theball will be repelled to the distance of four or five inches,more or less, according to the quantity of electricity ^When in this state, if you present to the shot the point ofa long, slender, sharp bodkin, at six or eight inches dis- ELECTROSTATICS 161 tanc
. The science-history of the universe . es diameter onthe mouth of a clean, dry glass bottle. By a fine silkenthread from the ceiling, right over the mouth of the bottle,suspend a small cork ball, about the bigness of a marble;the thread of such a length as that the cork ball may restagainst the side of the shot. Electrify the shot, and theball will be repelled to the distance of four or five inches,more or less, according to the quantity of electricity ^When in this state, if you present to the shot the point ofa long, slender, sharp bodkin, at six or eight inches dis- ELECTROSTATICS 161 tance, the repellency is instantly destroyed and the corkflies to the shot. A blunt body must be brought within aninch and draw a spark to produce the same effect. To prove that the electrical fire is drawn off by thepoint, if you take the blade of the bodkin out of thewooden handle and fix it in a stick of sealing-wax, andthen present it at the distance aforesaid, or if you bring itvery near, no such effect follows; but sliding one finger. •Franklins Experiment on the Action of Points. along the wax till you touch the blade, and the ball fliesto the shot immediately. If you present the point in thedark you will see, sometimes at a foot distance and more,a light gather upon it, like that of a firefly or glowworm;the less sharp the point the nearer must you bring it toobserve the light; and at whatever distance you see thelight, you may draw off the electrical fire and destroy therepellency. If a cork ball so suspended be repelled by thetube, and a point be presented quick to it, tis surprising to 162 ELECTRICITY see how suddenly it flies back to the tube. Points of woodwill do near as well as those of iron, provided the wood isnot dry; for perfectly dry wood will no more conductelectricity than sealing-wax. It is calculated that the density of electricity at an
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