Can anyone tell me what these are?

[oscar]

What's that on the top of the drawing? Is it just a mounting bolt or is there some feed hole though it ?
I think the best guess so far is an oil burning heater.
I presume there are no clues like maker or patent stamped anywhere, and can you describe the materials it is made of please!
Cheers,

Rob

Sorry it took so long.
This is the top of the wide part.


You can see the dished part where there may have been a ball bearing. Don't know material for sure, but the end cap looks like old pitted Ali to me.

[GEOFFREY]

Oscar, I have sent an email to Victorian greenhouse/hothouse expert and have referred him to your post. I don't know if he will respond. G.