oldlock wroteIt is surmised that the letters relate to dates, but there is no evidence to support that supposition that I have ever seen. It could mean a multitude of other things.
I am quite ill informed on the subject of locks but I have some information on the Acme keys from an article by Karl Jacobs in The Lock Collector Issue 46 which describes the diamond stamped Registered Design on the bow.
The circle above the diamond with letter ‘I’ is the material class. i.e. metal.
The top segment with 22 refers to the day. The illegible number on the left refers to the ‘bundle’?
The ‘C’ on the right is the year. i.e. 1870.
The letter in the lower section (illegible) refers to the month. For instance ‘C’ = January.
The numbers on the key it is suggested could refer to them being provided as part of a set.
The letters apparently refer to the 4 different key designs. There is a vast amount of information on these designs and on Cotterill’s in general but it would be improper for me to lift such from the Publications. (The Lock Collectors Association).
[unknown]
