Let a tin tube, of four or five feet in length, and about two inches
in diameter, be insulated by silk; and from one end of it let the
cork-balls be suspended by linen threads. Electrify it, by bringing
the excited glass tube near the other end, so as that the balls
may stand an inch and an half, or two inches, apart: then, at the
approach of the excited tube, they will, by degrees, lose their
repelling power, and come into contact; and as the tube is brought
still nearer, they will separate again to as great a distance as
before: in the return of the tube they will approach each other
till they touch, and then repel as at first. If the tin tube be
electrified by wax, or the wire of a charged phial, the balls will be
affected in the same manner at the approach of excited wax, or the
wire of the phial.