Wallace Supply Company's Rubber Stamp Flag Cancel

Yesterday, David Thompson found an interesting item on Ebay for the canceling of battleship revenue stamps.  The Wallace Supply Company of Chicago produced rubber stamp cancels in the form of a flag with the necessary identifying information to legally cancel revenue stamps.  The company promoted the rubber stamps through postcards (and perhaps other means as well), as the item in question is a postcard sent to the Exchange Bank in Ackley, Iowa.  

W. S. Co.

JUL  12  1898

CHICAGO

Inset from the upper left corner of the postcard.

I looked through a part of my collection to see if I could find an example and one showed up within  minutes of searching.  

M.  &  S.

MAR  25  1901

SAYBROOK,  ILLS.

This is an interesting little piece of 1898 revenues history, tucked away for sale under advertising postcards on Ebay, unlikely to be found by most 1898 collectors.  It is for sale for $50.