Rubber Office stamps
All clerks in offices dealing with invoices and cheques had a tree of rubber stamps that could be pressed onto an inked pad then stamped on to the paper. The message on the stamp thereby being transferred onto the paper (or cheque). The message on the stamp was of course printed in reverse mirror.
Here are three – but clerks may have had up to a dozen covering all eventualities of their job. This type of stamp was replaced by self-inking designs.