Primitive floating wick lamps, Northern Scotland, c 18th century.

UNITED KINGDOM - AUGUST 22: These two lamps, fashioned out of a hollow stone and a shell are examples of the most primitive lamps. These examples were probably used up until the 19th century, and may have been made in the 18th century or earlier. A natural hollow in a stone from the Shetland Islands, (left), has been enlarged for use as a floating wick holder. Part of an ancient whelk-type shell (right), has been chipped away to make a wick channel. This example was collected in Thurso, Caithness in Scotland. Such lamps have been widely used throughout the world. They were first used several thousand years ago, and would have burned grease, or oil made from fish or seagulls, and used a fibre wick. (Photo by SSPL/Getty Images)