I have a talc bottle with these marks, but I can only find other people looking for the same information. I can't find any thing except questions on these marks.
This is one of many marks used by the Barbour Silver Company, Hartford, Connecticut. Founded in 1892. They were one of the original firms that merged to become the International Silver Company in 1898.
International Silver continued to use many of the marks of the old companies into the 1930's. International Silver introduced the Barbour half circle mark in 1921. So, I'd say your piece dates from 1892 to about 1921.