Topic: Chance collectors only...

[keith]

Not mine but my photo,looks like a headlight,dimensions are on the object,any ideas please,

[chopin-liszt]

Is it not a Spiderweb bowl?

[David E]

Not a bad guess, Keith. At about 4-ins diameter these were light lenses and could have been used in a hand-held lantern, for example, and acting by focusing the light into a tighter beam - similar to lighthouse optics. But at about that size, in red, amber or green, they would have been for traffic or railway lights.

Headlight lenses have a different and more complex geometry, and were also made by Chance for Lucas headlight units.

[Anne]

Can I ask about the numbers shown...  I presumed that 6 3/8 D would be the diameter, so would the 3 ¾ F be the focal length of the lens?

[keith]

Thanks all,I've just spoke to my brother and he said it was sold as a railway 'light' what annoys me is he said it cost 99p !

[David E]

Yes, the 'F' indicates the focal distance.

Here's a 1946 Chance advert for traffic signal light lenses. This one is quite mundane compared to others of its adverts around the same time - they could be quite bizarre sometimes.