© Science Museum / Science & Society Picture Library
Colour engraving by Whymper taken from 'Phenomena of Nature', published in London in 1849 for the Society for Promoting Christian Knowledge. 'Those places on the earth's surface where subterranean fires have formed openings are called 'volcanoes'. A volcano is a sort of chimney, which occasionally pours forth streams of melted rocks, or 'lava', showers of ashes and sand, torrents of water and mud, and jets of steam and gas. The general form of a volcano is that of a regular cone, at the top of which is a circular pit, called the 'crater'.