OneGuyFromBarlick

Everyone seems to be away on holiday Gloria so I'll let it hang on a bit to see what happens.....

Here's a view of it from the other side....

Is a rope fed through it?

I can see why you thought that Gloria. No, what passed through the hole was a mating pear shaped piece of brass fastened to another surface. In effect capturing and holding this half of the artefact.

I’ll hold my hands up, I’ve no idea.

To hold a door open?

Kev has got it..... However not a door but an internal window shutter. During the day they folded back and became the lining of the window opening and these catches held them in place. Definitely an obsolete object!
Now we need a new one, any offers?

What is it?

Is the top one a coin , maybe a 50 cent coin?.
.
It looks to me like it is showing our Sydney Harbour Bridge, with fireworks above and below.
Probably just my imagination

Sorry Cathy I should have made it clear, the 50p coin is just for scale. The lower object is the mystery!

If there are no takers I shall knock it on the head.....

I'm guessing that it's a stud of some sort, large and decorative, possibly from a leather garment or boots?

You are dead on track Wendy. But not ornamental, these studs had an essential role on the transmission system of the mill....

Surely someone has an idea?

A drive belt stud or rivet?

Yes Wendy! Well remembered. One method of joining small flat leather drive belts in a transmission system.
Now we need a new object!