Ellis Machine Cancel, Washington, D.C., Jul 15, 1912. Clear postmark tying 1¢ Wash-Frank on picture post card, Very Fine and rare, postmark from a prototype machine developed by Warren E Ellis and briefly trialed at the Boston and Washington D.C. Post Offices, originally thought to be an experimental Doremus, known use of only a day or two in each city. Estimate  $150 - 200. $0 (Image)