Brilliant_ The Evolution of Artificial Light - Jane Brox [38]
Electricity's modern path can be traced back to 1600 in London, where Dr. William Gilbert, surgeon to Queen Elizabeth I, noted in his De magnete that sparks flew not only from amber but also from glass and precious stones, resin, sulfur, sealing wax, and more than a dozen other substances. He called these substances "electrics," from the Latin word electrum, in turn derived from the Greek word for amber, elektron. Gilbert died only a few years after the publication of his work, though in succeeding years other scientists, knowing of his findings, extended the list of electrics—among them diamonds, white wax, and gypsum—which remained just a list until Otto von Guericke, mayor of Magdeburg (now in Germany) created an electrostatic machine: a small, solid sulfur globe about six inches in diameter, set in a wooden frame, which he turned with an attached handle. When he both rotated and quickly rubbed his machine, it not only glowed and sent sparks flying; it also attracted light objects.
Guericke noted that electricity could repel things as well as attract them, and to the amusement of friends and visitors, he used his whirling globe to drive feathers across his drawing room, guiding them along until they rested on his guests' noses. For decades afterward, electricity—understood as a "virtue"—would remain largely an enigma that thrived as entertainment. An increased understanding of its properties only inched forward as a result of occasional observation of phenomena between amusements.
In the early eighteenth century, Englishman Stephen Gray established the conductive properties of electricity, having found, after rubbing the bottom of a glass tube, that its cork stopper had become charged. Through his experiments, Gray also discovered the insulating properties of some substances:
He suspended a long hempen line horizontally by loops of pack-thread, but failed to transmit through it the electric power. He then suspended it by loops of silk, and succeeded in sending the "attractive virtue" through seven hundred and sixty-five feet of thread. He at first thought that the silk was effectual because it was thin; but on replacing a broken silk loop by a still thinner wire, he obtained no action. Finally he came to the conclusion that his loops were effectual, not because they were thin, but because they were silk.
With this knowledge, Gray developed his "dangling boy" experiment, which in succeeding years became popular in drawing rooms across England. He suspended a young boy—swathed in nonconducting clothes except for his head, hands, and a few toes—by thick silk ropes. The boy held a wand with a dangling ivory ball in one hand and stretched out his other hand freely. When Gray set an electrified glass tube against the child's bare toes, the boy's hair stood on end, and brass leaf that had been piled on the floor beneath him rose toward the ivory ball, his extended hand, and his face. Gray might then invite members of the audience to stand on some conductive material and touch the boy, whereupon they would receive shocks.
The sulfur globes, and the glass ones that succeeded them, could only produce electricity; the first record of its successful storage dates from 1745. In Camin, Germany, Ewald von Kleist wrote of an experiment in a letter to a friend:
When a nail or piece of brass wire is put into a small apothecaries' phial and electrified, remarkable effects follow; but the phial must be very dry and warm. I commonly rub it over beforehand with a finger on which I put