No guess. It is Charles H. Meekel, turn of the century stamp dealer and publisher from St. Louis. Very active seller of V&A machine stamps. Bought his stock directly from the manufacturing companies. His hand stamp on the reverse on mint V&A stamps is as good as a certification.

Many of these were actually used on his mailings to collectors. Of course once the glue was wet the hand stamp was lost. Pine Lawn, MO was his outgoing post office and that hand stamp is a good indication for used stamps and covers.