Posted By:
Dan MathewsonThat is a great scan, Frank.
This is really interesting...Lemke's Catalog even says that the 1911 Pinkerton T5's vary in size and type of mount. (Some were mounted on cardboard backing, some had less substantial backing). The card I have here is the measured size of the 1911 T5 description, with a somewhat less substantial backing (but still pretty stiff-backed), and looks exactly like the card shown in the Lemke/SCD Catalog in every respect.
If yours showed a 1913 mailing stamp, and has those characteristics (which it appears to have), I would imagine it is likely from this Pinkerton issue also. Certainly it is not one of the later late-teens prints.