Always very popular and a very useful desk-top accessory. These large circular magnifiers actually are the condenser or magnifier from a Magic Lantern dating to around 1910; they are rescued, polished up and put back to use in the modern day.
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.
Wonderful condition, with a good magnification and a hefty piece to keep those papers in place. 4" in diameter x 2 1/2" high to top of dome.