Condensed fountain, c. 1750.

Condensation fountain, before 1753. Dr. Stephen Demainbray (1710-1782), a lecturer on natural philosophy, 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 compressed air forced the water out in a fountain, to collect in the upper basin.