feetlebum comptometers were indeed adding machines, you needed to know your decimals in order to work them, and they were a boon when working out the overtime to the last 'dot'. Highly paid by the then going rates - they could work our how many pennies, shillings, etc., needed for the wage packets (or at least that is how I remember them). Linotype operators do still exist, but only in the 'historical' sense, they are not needed now for commercial work as such, although give a better result than computers! (or so I am told by the fanatics who work them at Amberley Museum).