At the bottom of this letter scale is the maker's name and the indication that a patent is applied for. This patent application dates from June 4, 1968. The Design patent with number 214,464 dates June 17, 1969. It was granted to the firm Ketcham & McDougal Inc., Roseland, New Jersey, U.S.A.. Park Sherman Inc. was a division of that firm. This stable scale has a cylindrical rotating chart. The chart has the postal rates of January 7, 1968. This specimen is from before the patent date. On more recent specimens the received patent number is moulded into the bottom. The range is 16 oz. or 1 Lbs. The reading window gives side by side ounces, the first class postal rate, the airmail postal rate and the third class postal rate. The turning knob for adjusting is on the top of the housing. Because the figures of the Design patent don't differ from the actual letter scale, I've left them out here. Below some more photos of this letter scale.
Park Sherman letter scale
