Thomas is best know for the Feb 19th, 1867 patent found on its checks. This is a fairly early patent for a "shell" style large tag that accepts a smaller rectangular "insert". It is not known if Thomas was just a patent holder and the checks were made by someone else, or if Thomas actually manufactured the checks as well.

These are relatively hard to find and offer some variety to a collector. The "main" check has rolled side edges that accept an insert. The insert check may escape initial identification. My insert is extremely thin. It fits into my Vermont Central "main" check. Note that the Vermont Central name form is the early version which existed from 1848 until 1872. It is much harder to date The Long Island example because of the span of years for this name form. I do not know what the M designation on the Canadian Southern insert is for. If you know, please email me.
 

Thomas Patent baggage checks
Ornate Long Island example with the large form of patent hallmark	Vermont Central with very simple patent hallmark	Canada Southern Railway, a very thin insert