This curious fountain (often confused with Hero's fountain) is powered by the force resulting from the dilation of heated air. It is mounted on a varnished green wooden box, whose lid comprises two flaps. The box contains a square tin tank with a brass faucet on the underside. The tank holds a copper vessel with an upright tube rising into a brass sphere placed above the box. On the sphere is attached a brass cup with a faucet. A second tube inside the sphere runs into the center of the cup and was originally fitted with a nozzle (missing). For the fountain to operate, the sphere must be filled with water; the copper vessel should contain only air. Boiling water is poured into the tin tank through a funnel (missing) inserted in the box lid. The hot water dilates the air, which expands in the brass sphere as well. The water in the sphere is thus driven into the tube and springs from the nozzle into the cup. Provenance: Lorraine collections.