F4767-001

Lodestone Long Caption: The lodestone, a piece of magnetite, which is naturally magnetic, was vital in the early centuries of navigation to ensure that the ship's compass worked properly. Until the mid-18th century, when improved compasses were developed, compass needles lost their magnetism quite quickly and had to be re-magnetised by stroking a lodestone along the needle's length. Lodestones were often mounted in frames of brass, bronze or silver, and sometimes had an iron or steel keeper, a bar to help preserve their magnetic power. This lodestone has a brass frame with a carrying loop on top, and is 'armed' with two pieces of steel at the bottom, which help to increase the magnetic strength of the lodestone. Credit line: © National Maritime Museum, Greenwich, UK Object: NAV0713 Artist: unknown Date: circa 1600 Medium: lodestone; brass; steel Size: 51 mm x 51mm x 38 mm Click here to buy a bespoke print of this image.