Saw this today. 1930 home. In a ceiling at the basement level.

Googled Smart’s Brockville and only came up with cast iron implements.

Any ideas? Just for interest.

It’s a damper.
Never saw one before.

What Dom said.
Part of an old stove pipe damper?

Flue damper for wood stove. Here’s one sold at home depot:

Flue damper for wood stove. Here’s one sold at home depot and ebay:

Thanks guys - learned something new today!

Thanks all. Always something learned

The original picture did not indicate the size of the object in question.
I assumed it was some form of electrical receptacle!

Like Bryce, my first impression was it might be some sort of air vent. It is interesting to see different types of materials that are not commonly encountered from many years past!

On another note it was also interesting to research and find more related products like Len did by a Google of “Smart’s Brockville” and his metal forging company.

When there is a name associated on an object and the type of material is clear, browser research can help at time.
Cast iron, Cast iron forgings and foundry. The former uses pressure during manufacturing and the later maynot.

I use to walk or bike the lachine canal. There was a small cast iron forging company there. The doors open on hot summer days. You could watch and hear the forging of red hot blocks of steel.

In my experience some dampers had sizings labels while others did not.

The flue may not be abandoned properly if it was left like that. There could be soot and other atmospheric contaminants in the vent. I leave that up to your discretion.