### Circa 1888 ????? ###

[torrens]

Seconding Ogilkes' suggestion this looks identical to a "T"bar Jean Marck Gem I had a while ago, except yours is much shinier! The 1888 patent stamping is sometimes assumed by sellers to be a manufacturing date. The JM Gems were made from the late 1880's to the 1930's with very little change. Mine was the large No 3 in .177 and did a stonking 8ft lbs.
torrens