Puckerings has dated this piece to the 1900s.

This one is made from polished brass and is excellent quality having a lovely domed lens rather than flat on top, un-marked but probably by Optimus.
It's not often I find something different about these when I can get hold of them, this one is rather different with the domed lens being sprung. The other outstanding feature is the presence of an English design registration number which allows us to date it accurately to the year 1907; this is the only one I have had with a registration number, probably because of it's unusual sprung lens.

Wonderful condition, with a good magnification and a hefty piece to keep those papers in place. 4 1/4" in diameter x 2 1/2" high.
Item ID: 36040
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Puckerings has dated this piece to the 1900s.
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