slogan machine cancel with "Stamford Conn. Oct 19 1936 6:30PM" dial on blank card, very fine, a few of these cancellation proofs were printed as a trial of the dies at the Universal Stamping Machine Co. in Connecticut, Stamford was used in lieu of a Canal Zone datestamp as one was not available at the plant, the trial was conducted in the presence of a Canal Zone inspector on February 5, 1937, as few as five known