I found a nice wooden triangular rule today for 50 cents, picked it up. It advertises the Barber-Greene coal handling equipment. Barber-Green was started in 1917 I think and eventually became known for their asphalt paving equipment. I thought the phone number was a little weird, it states "Phone State 5923." I thought this was a 4 digit number and began researching the time when a 4 digit number would have been used and found an interesting tidbit of info I had never heard before.
Phone numbers originally had only one digit, then 2, 3 and so forth as needed. When they realized that 4 digit numbers were not going to be enough they decided to go with 3 letters and 4 numbers, I think this is when letters were added to the dial pad. In order to make the 3 letters easy to remember they assigned a word to it that had those letters as the first three. For example a phone number would be advertised as "Harrison 9676". To dial it you would dial HAR-9676. I am not sure when this started but it was prior to 1930 and ended by 1947. (TELEPHONE NUMBERS) The telephone number on my rule is "State 5923", or STA-5923. Probably from sometime in the '20s. Of course none of this is researched in depth, it is just my best guess from the info I found.
rule full.jpgRule phone.jpg