The sources of a river are lost in the clouds of the mountain, but it is usual to derive its waters from the lakes or springs which are its fountain-head. In the same way the origins of our knowledge of electricity and magnetism are lost in the mists of antiquity, but there are two facts which have come to be regarded as the starting-points of the science. It was known to the ancients at least 600 years before Christ, that a piece of amber when excited by rubbing would attract straws, and that a lump of lodestone had the property of drawing iron. Both facts were probably ascertained by chance. Humboldt informs us that he saw an Indian child of the Orinoco rubbing the seed of a trailing plant to make it attract the wild cotton; and, perhaps, a prehistoric tribesman of the Baltic or the plains of Sicily found in the yellow stone he had polished the mysterious power of collecting dust. A Greek legend tells us that the lodestone was discovered by Magnes, a shepherd who found his crook attracted by the rock.
However this may be, we are told that Thales of Miletus attributed the attractive properties of the amber and the lodestone to a soul within them. The name Electricity is derived from ELEKTRON, the Greek for amber, and Magnetism from Magnes, the name of the shepherd, or, more likely, from the city of Magnesia, in Lydia, where the stone occurred.
These properties of amber and lodestone appear to have been widely known. The Persian name for amber is KAHRUBA, attractor of straws, and that for lodestone AHANG-RUBA attractor of iron. In the old Persian romance, THE LOVES OF MAJNOON AND LEILA, the lover sings--
'She was as amber, and I but as straw: She touched me, and I shall ever cling to her.'
The Chinese philosopher, Kuopho, who flourished in the fourth century, writes that, 'the attraction of a magnet for iron is like that of amber for the smallest grain of mustard seed. It is like a breath of wind which mysteriously penetrates through both, and communicates itself with the speed of an arrow.' [Lodestone was probably known in China before the Christian era.] Other electrical effects were also observed by the ancients. Classical writers, as Homer, Caesar, and Plutarch, speak of flames on the points of javelins and the tips of masts. They regarded them as manifestations of the Deity, as did the soldiers of the Mahdi lately in the Soudan. It is recorded of Servius Tullus, the sixth king of Rome, that his hair emitted sparks on being combed; and that sparks came from the body of Walimer, a Gothic chief, who lived in the year 415 A.D.
During the dark ages the mystical virtues of the lodestone drew more attention than those of the more precious amber, and interesting experiments were made with it. The Romans knew that it could attract iron at some distance through an intervening fence of wood, brass, or stone. One of their experiments was to float a needle on a piece of cork, and make it follow a lodestone held in the hand. This arrangement was perhaps copied from the compass of the Phoenician sailors, who buoyed a lodestone and observed it set towards the north. There is reason to believe that the magnet was employed by the priests of the Oracle in answering questions. We are told that the Emperor Valerius, while at Antioch in 370 A.D., was shown a floating needle which pointed to the letters of the alphabet when guided by the directive force of a lodestone. It was also believed that this effect might be produced although a stone wall intervened, so that a person outside a house or prison might convey intelligence to another inside.
This idea was perhaps the basis of the sympathetic telegraph of the Middle Ages, which is first described in the MAGIAE NATURALIS of John Baptista Porta, published at Naples in 1558. It was supposed by Porta and others after him that two similar needles touched by the same lodestone were sympathetic, so that, although far apart, if both were freely balanced, a movement of one was imitated by the other. By encircling each balanced needle with an alphabet, the sympathetic telegraph was obtained. Although based on error, and opposed by Cabeus and others, this fascinating notion continued to crop up even to the days of Addison. It was a prophetic shadow of the coming invention. In the SCEPSIS SCIENTIFICA, published in 1665, Joseph Glanvil wrote, 'to confer at the distance of the Indies by sympathetic conveyances may be as usual to future times as to us in literary correspondence.' [The Rosicrucians also believed that if two persons transplanted pieces of their flesh into each other, and tattooed the grafts with letters, a sympathetic telegraph could be established by pricking the letters.]
Dr. Gilbert, physician to Queen Elizabeth, by his systematic researches, discovered the magnetism of the earth, and laid the foundations of the modern science of electricity and magnetism. Otto von Guericke, burgomaster of Magdeburg, invented the electrical machine for generating large quantities of the electric fire. Stephen Gray, a pensioner of the Charterhouse, conveyed the fire to a distance along a line of pack thread, and showed that some bodies conducted electricity, while others insulated it. Dufay proved that there were two qualities of electricity, now called positive and negative, and that each kind repelled the like, but attracted the unlike. Von Kleist, a cathedral dean of Kamm, in Pomerania, or at all events Cuneus, a burgher, and Muschenbroek, a professor of Leyden, discovered the Leyden jar for holding a charge of electricity; and Franklin demonstrated the identity of electricity and lightning.