rocking letter scale
This non flat, but convex spring steel strip is a ruler and a letter scale. Putting a blue transverse stripe of the scale equal to the edge of a desk or table delivers the determination of the weight group. When the scale rocks the letter is heavier then the chosen amount of ounces. The scale has four limits: 1, 2, 3, and 4 ounces. The postal rates for Air Mail and First Class are given. The First Class rate of 4c per ounce was valid in the period August 1 1958 till January 7 1963. The directions for use are printed on the scale. The ruler has a capacity of 9 inches. Each inch is subdivided into eight parts. Probably this letter scale was a promotional gift. It has an advert for the Miami County Savings & Loan League. The bottom is left unprinted. Below some more pictures of this rocking scale.
