Miss Barzume and Mr. O’Halloran worked at the Post Office Department with Henry Hammelman.
Hammelman’s first known FDCs were for the new parcel post stamps in 1913. His last covers were made in 1948 to mark the introduction of a new air mail parcel post system. He was into first days of issue, first days of rates, and first flights. Besides being a cover servicer and a Nassau Street dealer, he was also an exhibitor who was the first person to exhibit a FDC exhibit at a major stamp show.