In examining, now, the history of the rise of electrical science we find, as just mentioned, the vast gap of over two millenniums between the discovery of the attracting power of rubbed amber and the mere extension of man's knowledge so as to include other substances. The philosophers Boyle and Otto von Guericke, who were active during the latter half of the seventeenth century, added a mass of new data in this line. Boyle, moreover, discovered the equivalence of action and reaction between the attracting and the attracted body, and that the rubbed amber or other "electric" retained its attractive powers for a certain period after excitation had ceased.
Otto von Guericke made a vast step forward by constructing the first electrical machine, in a crude form, truly, but which proved of the utmost service in adding to our knowledge of the properties of electricity. His machine was constructed very simply of a globe of sulphur mounted on a spindle, which could be rotated by means of a crank; the operator applied friction with the hand, his body receiving a positive charge, while the surface of the sulphur acquired a negative. The fact of the two electrifications being separated at the surface of the sulphur was not, however, known at the time; the only charge that Guericke observed being that appearing on the sulphur. The reason for this was that the latter, being a nonconductor, any electricity generated upon it was compelled to stay there, for a certain time at least, and consequently accumulated so as to be observable; whereas the opposite electrification flowing into the operator's hand continuously escaped to earth without giving any sign of its presence. Had the operator stood upon an insulating support, the electrification would have accumulated on his body as well as upon the sulphur. Guericke made the discovery that a light body, having been once attracted to an electrified surface, was almost immediately repelled from it, and could not be again attracted without having its imparted electrification removed by contact with an uncharged surface.
Sir Isaac Newton, about 1675, made an interesting application of a principle allied to this. He used a hollow, drum-shaped contrivance with glass ends and a very short axis, into which he put a number of fragments of paper. On briskly rubbing the outside of the glass with a piece of silk the paper was caused to "leap from one part of the glass to another and twirl about in the air." This was repeated in 1676 before the Royal Society, to the great edification of that learned body.