THE ELECTRIC TELEGRAPH.

9

Theophrastus (321 b. c.), in his writings, describes thisproperty.

Pliny (a. d. 70) refers also to the same. He speaks ofpieces of amber that “ attritu digitorum acceptd vi calorisattrahunt in se paleas et folia arida ut magnes lapis fer-rum.”

Similar remarks may also he found in the writings ofPriscian and Solinus .

Salinasius, in his commentary upon Solinus , asserts that theword karabe, by which amber was known among the Arabs , issaid by Avicenna to be of Persian origin, and to signify thepower of attracting straws.

It does not appear that any of the ancients reasoned uponthose observed effects; they merely observed, and recordedthem as facts.

Dr. Gilbert, however, at the commencement of the sixteenthcentury, instituted a series of experiments upon the subject.He found that the property possessed by amber was not con-fined to that substance alone, but belonged to several otherbodies, such, for instance, as the diamond and many otherprecious stones, glass, sulphur, sealing-wax, resin, &c.

Boyle found that warming these bodies increased the effect.

To Otto Guericke , of Magdeburg , who was also the inventor of the air-pump, is due the invention of what is commonlycalled the Electrical Machine. This philosopher mounteda globe of sulphur upon an axis, and, on turning the globeround, applied friction to it. By this means he detected thatstrong electrical excitation was accompanied both by light andsound: he also discovered that after a body had been electri-cally excited, and another light body brought in contactwith it, a repulsion ensued. Many other of the now well-known phenomena of attraction and repulsion were demon-strated and recorded by this philosopher.

In 1675, Sir Isaac Newton made several important dis-coveries relating to the above, and noted down the effectsobserved in his experiments on the subject.

a 5