Go on then, what were these for?

[wolfracesonic]

Just retrieved these from under the floorboards, bog standard 30s semi, I’m insulating under there and they were in the way. I’ve known they were there since I moved in but left them be.





Both glass, the larger is 14’’ diameter x 1 1/4’’ thick and is literally rough around the edges, the smaller one 12’’ x 1 1/8’’ thick and more finished; the wooden case goes with them I think.
No sure what they’re for, maybe used in a laboratory as an inert surface for preparing things?
If anyone can reply ‘No idea what they are but there is a pair on Ebay for £5000’, I’d be most grateful

[V8FGO]

Given the sizes, I would think they are mirror blanks for a a reflecting telescope.

[Racing Sparrow]

I'd go with that thought too, certainly if they have a convex face.

[wolfracesonic]

Interesting, though I have just put a steel ruler across them and they both seem pretty flat, both faces.

ETA Just had a Google and you could both be right! I’d never have guessed in a million years!

[Jo-say8k]

Im curious as to your knowledge of them being there but left them??

[wolfracesonic]

^ I had no use for them, they weren’t hurting anything so I left them; till today when curiosity overcame me!

[sherman]

If they are flat they might be port hole glass from a ship.
The edges wouldnt need finished as they are clamped into a frame.

Edited by sherman on Saturday 27th December 13:31

[RacingStripes]

Titanic porthole glass. Definitely.

[The Gauge]

Eye lenses for a giant?

[Essel]

A previous house owner saw those in a skip and thought "I've no idea what those are, but it looks like they'll come in handy one day", then had to hide them under the floor as his wife was on his case about cluttering the house up.

[WrekinCrew]

V8FGO said:

Given the sizes, I would think they are mirror blanks for a a reflecting telescope.

Racing Sparrow said:

I'd go with that thought too, certainly if they have a convex face.

14" is pretty big for a home-made reflecting telescope, and the mirror would be concave, not convex.

[netherfield]

And today we will be looking through the round window children.

Play School if you're old enough to remember

[Simpo Two]

Normally when faced with a puzzle like this I post it on PH for the answer... so that's me out.

From the above ideas, porthole glass makes sense - very thick but lower portholes would take a battering from the waves and maybe toughened glass wasn't invented when they were made.

[wolfracesonic]

I’ve seen two for sale on eBay, very similar thing, albeit smaller and they’re listed as mirror making blanks, so the initial suggestions may be on the money. I’m going to clean them up in the morning and see if I can find a use for them: if I can’t I may contact the local astronomical society and see if they want them (and be asked ‘why would we need a couple of ships portholes?’). If they don’t I may put them back under the floor for someone else to puzzle over when I’m gone.

[M4cruiser]

They are upgrades for a Rega Planar turntable.

[x type]

They could be old railway lantern lenses ?

https://www.google.com/search?client=firefox-b-d&a...

some were shaped , others were flat

[mac96]

M4cruiser said:

They are upgrades for a Rega Planar turntable.

Just need to drill the hole!

[dickymint]

wolfracesonic said:

I ve seen two for sale on eBay, very similar thing, albeit smaller and they re listed as mirror making blanks, so the initial suggestions may be on the money. I m going to clean them up in the morning and see if I can find a use for them: if I can t I may contact the local astronomical society and see if they want them (and be asked why would we need a couple of ships portholes? ). If they don t I may put them back under the floor for someone else to puzzle over when I m gone.

Make sure you leave them a link to this thread

[NDA]

Does your property have a cellar or coal bunker?

[vaud]

NDA said:

Does your property have a cellar or coal bunker?

Or an unexplained bunker in the garden with a big rock?