Copper syphon or 'Tantalus' cup, and glas, early 18th century.
© Science Museum / Science & Society Picture Library
The small copper vesel has a handle made from a piece of hollow copper pipe which acts as a syphon. Thomas Desaguliers suggested filling it with water, throwing in an apple or orange to raise the level above that of the top of the handle, and watching the water run out through the handle until the vesel was almost empty. These instruments are asociated with Dr Stephen Demainbray (1710-1782), a scientific lecturer of the 18th century.