Steve Williams from Norfolk would like to know what this strange brass object is for. Steve says 'It is very heavy brass and seems to consist of two heavy counterweights which keep the small socket vertical to the stem if tilted (north south but not east west). No idea what would fit in this small socket, it has a knurled knob to tighten and on top of the long brass stem there is a dish shaped knurled affair. It looks as if it should be screwed down to something and has a brass plate and threaded washer.

Steve does not think it is nautical.