English: Drawing of the first electromagnet, invented in 1824 by British scientist William Sturgeon. This was his original drawing from his 1824 paper to the British Royal Society of Arts, Manufactures, and Commerce. It was made of 18 turns of bare copper wire (insulated wire had not been invented) on a U-shaped lacquered iron core about 1 ft (30 cm) long and 1/2 inch (13 mm) diameter. When the wires were connected to a single cell copper-zinc-acid battery, the electromagnet could support 9 pounds. The little cups contain mercury and were an early method of making an electrical contact between wires. The one on the left acts as a power switch. Alterations to image: converted from JPG to 32color PNG.