These signers are not entirely anonymous. They are listed in civil service records, usually just name, date of birth, date hired on, date retired. Some of those ladies kept working for the Department of Finance, just signing away, until they were 80 or more. Pension plans weren't too good in those days, I guess. Information on these people has been published in CPMS Journals years ago - see for example Ruth McQuade's article, page 71, 1987 Journal.
Caroline Longley Bennett (signed notes shown above) was born 7 Nov. 1845, hired 20 Jan. 1884, last year of known employment was 1920. By this time notes were all machine signed, so she was probably "laid off". (How easy would it have been for a girl of 75 to find another job, I wonder?) With 36 years of service, her signature ought to show up on a wide range of Dominion notes.