555 Castlehill, Edinburgh EH1 2ND
This ornate drinking fountain marks the site on Castle Hill where the mathematician George Sinclair constructed a cistern to supply water to the city of Edinburgh in around 1675. The original reservoir was demolished to make way for a new, larger one in 1849. Sinclair was professor of Mathematics at the University of Glasgow from 1654 to 1666. In 1655 he made some very early descents in a diving bell off the Isle of Mull. He was not only a leading mathematician and engineer, but also an expert on demonology and author of Satan’s Invisible Works Discovered (c.1685).