Condensed fountain, c 1750.
© Science Museum / Science & Society Picture Library
Dr Stephen Demainbray (1710-1782), the science lecturer, had several fountains but only two have survived. This example dates from about 1750. The spherical hollow chamber was partially filled with water and air was then forced in using a pipe and stopcock. If the pipe ended below the surface of the water when the stopcock was opened, the compresed air forced the water out in a fountain, to collect in the upper basin.