OneGuyFromBarlick

Is it for checking specific gravity of distilled water?

Ive got to giver it to you Gloria because you are so close. It was for checking the specific gravity of a sample of boiler water because that gave us the proportion of dissolved solids, the elements that resulted in scale. We used boiler treatment to precipitate those elements out as sediment which collected in the bottom of the boiler and could be blown out each morning before we woke the fires up.
Now we need another object!

This is probably to easy for you all, but what is it?

A pressure relief valve?

Spot on, it’s off a 500hp steam engine at Grane Mill Haslingden.

What is this?