Charcoal immersion bath heater, French, c 1850.
© Science Museum / Science & Society Picture Library
In the days before gas geysers and piped hot water, this charcoal heater was used to heat the cold water for a bath. At the bottom of the bulbous body is a fire-grate into which charcoal is put and ignited. Removing the lid of the main body allows the smoke to escape. Air for combustion enters beneath the grate through the two breathing tubes. The whole vesel is then immersed in the cold bath with the breathing tubes above water level and removed when the water is hot.