Antique French fireman's hose nozzle.
It is made of brass and copper, with a lever to adjust the water pressure and an opening and closing mechanism to control the flow.
It contains various inscriptions to indicate how it works.
It also contains the inscription: 'A de Bois Breveté S.G.D.G.'.
"A de Bois Breveté S.G.D.G." is a French trademark that was used in the 19th and early 20th centuries to mark various types of metal objects, including tools, instruments and weapons.