Salter letter scale
This small letter scale made by Salter probably was intended for the French market. This letter balance is pictured as No. 10 in a Salter catalog from 1899. The length of the front plate is 73 millimeters, the front plate width is 21 millimeters. The 50 grammes scale has a stripe for each gramme, and very special also stripes of measure at respetively o 7½, 12½ and 22½ grammes. In France 7½ and 22½ grammes have been postal rates limits for sure between 1833 and 1875 for letter mail to Great Britain and for letter mail to Prussia. Searching postal rates history revealed that during the period 1833 till 1875 there was an agreement, a Postal Union, for mail between Great Britain and France wherein the weight limits 0-7½, 7½-15 and 15-22½ grammes are stated. I'm still looking for an explanation for the 12½ grammes and the period of validity. Already earlier a slightly larger Salter with double the weighing capacity was presented, see Salter's Letter Balance.
Below some more pictures of this letter balance.
weighing a letter
