Most Hammond typewriter serial numbers do not follow any known order or arrangement. Unfortunately no records survive that detail how these numbers were organized, but we do have some clues.
Hammond No. 1’s have their serial number predominantly beneath the right ribbon spool. The 1b, 2, 12, and early Multiplexes stamped the serial number on the left rear leg of the machine’s frame. You could also find it during this period stamped on to the bottom of the one of the machine’s feet.
Machines were often turned in to be remodeled with the latest advancements. Typically this would be reflected with the serial number stamped again beneath the right ribbon spool, and the word REMODL or REMOD.
When the company began producing aluminum machines they added a prefix of AL. The folding multiplex simply had an F on the end of the number. for reversible type machines, an R was affixed to the end.