I wonder if the light source is coming through the actual ceiling itself...ie.the material used???..just a thought...and what is that object in the ceiling above the alcove at the end.

Derek.
This was mentioned back on the first page. A couple of people speculated that is was an eagle, but, to quote myself:
I have to say I'm not sure about the 'eagle'. To me, it looks like a dome that extends up into ceiling with something hangin down in the middle (the white part). The perspective gives it the oval shape and the cut out gives the shape of wings! I've seen a smililar thing before.
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Interesting thinking on the museum. Although surely the dating on the photo doesn't work out with this - i.e. the room seems to be 'typical' of the era we estimate the photo to be taken in, so you wouldn't put what would be a modern room (of the time) in a museum - it wouldn't be history yet! Probably not the best way to explain what I mean :S
Nice researching there gadget! I need to check with Kirsty when she's around, but I believe that photo does in fact show the possible owner of the glass negative - I can't say for sure though.
Ooh, that's something to look into Nina - dating the photo by using the others in the picture!
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I've got to agree Denn, the lighting in the photo is certainly intriguing me - especially now you've pointed out all those odd shadows that would need multiple light sources to be cast. A bounce flash, bounced of the ceiling might explain this, as the ceiling is curved, it would explain the various angles the light seems to come from. Also might explain why the original negative is pretty dark and had to be lightened?
Keep the amazing ideas coming people - Kirsty and I are really keen to get to the bottom of this and are always calling to each other when we notice a reply!
Hadyn
EDIT: Tomkin, I'm not sure the temporary ceiling idea of yours works with regard to the stone looking wall (particular that mural/panel) and the two doors at the back of the room. I could be wrong though, but that's just my reasoning! Also, if you have the time, it's well worth reading what everyone has had to say about the image!