Hand-coloured aquatint by Robert Havell after George Walker from 'The Costume of Yorkshire' by George Walker, published 1814 by Robinson & Son of Leeds. The image shows women collecting leeches for the practice of bloodletting. Bloodletting was intended to drain 'poisons' or exces blood from the body in order to restore the balance of the humours of the body, a popular medieval therapy which was practised as late as the 19th century. Placed on the skin, leeches can drink five times their own weight in blood, chemicals in their mucus stopping the blood from clotting. 'The Costume of Yorkshire' recorded the social customs, pastimes and occupations of the people of Yorkshire at the beginning of the Industrial Revolution.
© Science Museum / Science & Society Picture Library