Vintage WW1 monocluar by Manhatten Optical Co. with Military Arrow mark

A monocular made by the Manhatten Optical Company, sadly not in the greatest condition but very interesting nonetheless. The lenses are intact, though quite dirty. They do work in bright light, and are now adjusted by sliding the eye lens in and out. Original parts are missing/broken. I think the wood effect covering was a mid-century "improvement(!)". The piece has a serial number - M 1222 - on one end and a military Arrow mark on the other end. It looks also as though a name has been scratched onto it - Lumley.  If you right-click over a photo and choose view picture, you will see an enlargement of the picture. The monocular is approx 10 cms long.