postal steelyard
or
balance with unequal arms
for letters

maker: unknown, England bruine lijn

English balance, the scale up to 16 ounces is on this beam side

This balance with unequal arms, also called steelyard, comes from England. It shows no brand or logo. The model is very similar to No. 367 of the firm W & T. Avery Limited, of Birmingham, England. I saw a drawing of the model in the 1903 Avery catalog as well as the 1909 one. Four capacities were available: 4 oz, 8 oz, 16 oz and 32 oz. The brass balances stand on a mahogany base plate. Metric versions were also available to order. In an article titled Avery Postal Steelyard by G. & R. Lipfert in Equilibrium of 1991, on pp 1514-1518 it is stated that this balance is already depicted and described in the 1850 catalog and later also in the 1862 catalog, with a mahogany base plate or slightly more expensive with a marble base plate. In the catalogs of 1878 and 1880, the roundings of the mahogany base plate are the same in shape as those of the base plate shown here.
The balance shown here weighs up to 16 ounces. On one side of the balance arm, the notches are marked with the following weights: ¼, ½, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 , 14,15, and 16 ounces.

English balance, the scale up to 32 pence is on this side of the beam

On the other side, next to those notches are the English postal rates for letters in pence, denoted by the capital D: ½oz 1D, 1oz 2D, 2oz 4D, 3oz 6D, 4oz 8D, in each oz 2D more, up to 16oz 32D. This English letter rate was valid from January 10, 1840 to April 1, 1865.
At the bottom of this page, the balance is shown next to the similar, but simpler and much smaller balance previously shown with a four ounce capacity.
The base plate is 25 x 12 x 3.3 centimeters. The total balance arm is 35 cm long. The letter plate measures 12.5 x 13.7 cm. The counterweight is 3.5 cm around and weighs 196 grams together with the suspension. The spire of the hinge is the highest point at 21.6 cm. The weight of this balance with unequal arms is no less than 1369 grams.
Below are some more images of this old English letter scale from the period 1840 - 1865.

the spherical weight can be moved along the beam
from notch to notch

animation: moving the spherical weight
shows the extreme positions of the balance beam
[move the pointer over the photo]

the oval limits the movement of the balance beam

the graceful end of the balance arm with the suspension of the letter plateau	the solid knife-edge bearing of the balance	the moving balance parts are disassembled here
image from the 1903 Avery catalog	the balance has a mahogany base plate or mahogany slab	image from the 1909 Avery catalog
unloaded with counterweight at zero ounce	loaded with counterweight at 15 ounces	unloaded with the counterweight at six ounces
view at the pence side of the balance	counterweight at the 32 pence position	view from above
the brass letter tray	the suspension point of the letter plateau and the pivot point of the balance	the solid knife-edge bearing of the balance
the capacity of 16 ounces is stated on both sides of the beam	the capacity of 16 oz on the other side	the indication ounce is next to 16 - 15 - 14 - 13 - 12
the indication pence is behind 20 - 22 - 24 - 26 - 28 - 30 - 32	start of the scale with ¼ and ½ followed by 1, 2 et cetera to 16	bottom of the base plate with the nuts of the uprights
the balance in an extreme position	the balance with detached letter plate	here the balance arm with the counterweight is also disassembled
the bottom of the letter plate	counterweight and knife-shaped suspension part together 196 grams	the detached letter plate