Hot spring in the Solfaterra, near Naples, Kingdom of Naples, c 1760.
© Science Museum / Science & Society Picture Library
Hand-coloured etching by Peter Fabris (active 1768-1779). Illustrated plate from William Hamilton's studies of Italian volcanoes, 'Campi Phlegraei' (published in Naples, 1776). The (1) source of the hot spring, 'Pisciarelli', and (2) the hot bath, within the cone of the volcano Solfaterra. Hamilton reports a temperature of up to 101 degrees fahrenheit for this water. Based on letters to the Royal Society, Hamilton's book was a more precise account of the nature and effects of volcanic activity than had previously existed.