My brother-in-law brought me a very cool housewarming gift yesterday. This is an egg-grading scale from the 1920's:
Its purpose is to quickly grade eggs according to weight. A heavier egg will lift more of the horizontal tin strips. The weight is indicated by figures etched to the left of the tin strips. These figures represent the egg grades. The egg I placed on the scale measured 28 on the scale, this means that a dozen of those eggs weighs about 28 ounces.
This scale was used by small egg producers to grade their eggs. Based upon the grades, these eggs were then bartered for credit at the local store.
The close-up didn't turn out as well as I had hoped, but etched on the front of the scale is its original patent date of June 24, 1924. Very cool.
A bit more information and some additional photos can be found here.