Help. Could this be what it looks like ?

[fernando]

The sellers thinks ( just thinks ) this could be one of these weight and chains used in prisoners.
The ball is cast iron, with a visible seam, and measures some 14 cms ( nearly 6" ) in diameter.
Looking at the marks left, it could have been that the chain was held to the ball by two rings, instead of the actual one.
This chain presently measures some two meters ( over two yards ) and was once mended, as it has two different patterns. This could be because part of its links was worn out, as are the remnant ones, which supports the hipothesis that it was a prisoner's chain, as it was long tensioned and dragged, instead of being a fixed sort of counterweight, like those of windmills, or other equipment
The all through orifice is over an inch wide, and had a later wooden plug stuck in the back end ... wonder why.
Skipping the reason for the plug, I wouldn't know the purpose for the orifice, which would naturaly be the key to identify this device.
Is there anyone familiar with this type of things ?
... Not from personal experience, of course
Would this be an actual prisoner chain, i will rush to buy it. I think a fair price can be managed.
Any help would be much wellcome.
Fernando