Sea Mine? Switch for a sea mine?? Any ideas?

[Knowlehill]

I bought the cylindrical 'mine' many years ago in Portobello Road and have no idea what it is. The ring of switches around the rim are numbered sequentially and are sealed against water ingress. Inside there is nothing to suggerst it held a charge or any arming mechanism. The lid is held on by a series of bolts against a watertight seal. I had a theory that it was a contact switch that floated at a set depth connected electrically to a larger charge on the sea bed. No other markings/stampings. Well made. Any thoughts greatly appreciated! David.:xd:

 

[Sprockets]

Dear Knowlehill,

I have a suspicion that it may be a so-called "Circuit Closer" for a Defence Minefield protecting a harbour, etc. It would only be energised when there was possible intrusion by the enemy, and would usually activate a moored mine in which it was contained. Your surmise about about being an impact-switch is probably correct, but normally there would be no need to utilise a bottom mine, with it's lower efficiency, as the mines could be set to the correct depth at the time of laying. Mcevoy (?) is a name that I vaguely remember as being the designer of one Circuit Closer .


Regards,

Martin.