Avery Weight - 6ib 1oz 9 dram

[Susiekins]

I have an Avery weight - with 6lb 1oz 9 dram marked on the top.  Any ideas what this might have been used for? 

[Hippy]

Possibly for calibrating weighing machines. When normal weights are made they are usually of iron or bronze with a small hole drilled underneath which is then filled with lead. This small lead plug is then drilled out a small bit at a time and the weight tested on a known good machine until the correct weight is achieved (well very nearly).

The other way round, to make sure a weighing machine is set correctly, requires a weight of known precice value. This does not have to be a whole unit (e.g. 7oz, 5Kg) but can be anything that the machine is capable of recording. So a test weight is produced of abitrary value and its exact weight determined from a known good machine, and this then used to set other machines.