Dear Alistair, It has always been a bit of a puzzle how four great hammers could fit inside a bell as strikers inside bells are usually called clappers. At www.lighthousetour.com under buoy, there is an excellent photograph of a North American bell buoy clearly showing four great hammers hanging down outside the bell on long shanks, which clearly would ply the outside of the bell with great force in any sort of rough sea, the bell itself being placed low down in the frame.. As the brother of a church bell, I have always assumed the bell in the Bell Buoy would be hanging from the top of buoy frame and the clapper/s would strike it on the inside as the buoy moved, and there are one or two bits of information confirming this, but I have not been able to find a description or illustrationas to how a Trinity House Bell Buoy was actually made. The illustrations of buoys in the 1911 Encyclopaedia Brittanica are not detailed enough. Would it be possible for you to ascertain how a Bell Buoy of 1896 was constructed for Trinity House? As a sideline there is the famous poem about Ralph the Rover stealing the bell off the Inch Cape Rock and being wrecked upon it himself in consequence at a subsequent date. Regards Richard Haythornthwaite.