Bob Smith, underwater archaeologist from U.K., wrote this: "It's 10 the number ten. \you often find battery numbers written sideways on this part of the cannon. Could be for aboard ship or on land battery. "
So it seems this gun served as gun no. 10 in one battery and gun no. 7 in another. If another similar gun in one of Michigan's museums has a number in the same style in the same location, that may mean it was once in the same battery.
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