532. English Balance Scale. Roberval principle. Equal arm. 3-1/8" high. Metal. Base 8-15/16" wide x 3-5/8" deep. Oblong letter plate; saucer-shaped tray for weights. End of base, shaped as receptacle, holds five nested weights. Eliptical indentation on face of base bears label with printed postal rates. Markings: "Airweigh Letter Balance. Made in England." Mfr: Helix (Universal) Co. Ltd.