Expanding a little on what Sam and BB have said, the 'reamers' 'rimers' or 'rinders' (take your pick on spelling) go back to the days before woodscrew sizes were standardised. In the dim and distant days of the 19th century, it was apparently not uncommon for the person fitting (say) hinges and lock to a door to have to 'ease' the screwholes in the ironmongery to fit the available screws. Also, centre-bits of the old type quite often drill holes that are a tad large to their nominal size, and which may require 'easing' to fit whatever may be going in them. Thus, the well-equipped joiner would have a set of reamers (one each for wood, iron and brass) and a set of countersinks (one each, ditto) to ensure he could fit whatever ironmongery came his way.
With standardisation in the early 20th century came improved fit of parts bought from different suppliers, and the need for 'reamers' to fit ironmongery properly dwindled. They still crop up a lot on the secondhand market; almost every vintage bit roll seems to have at least a part set of rimers and countersinks.
There are three types of reamer, the square cross-section ones are for iron (wrought or cast - mild steel didn't come along until later in the 19th century), a solid half-round cross-section for brass, and the hollow half-round section ones for wood. There were also three types of countersink; snail type for wood, rose type for brass, and the flat type for iron.
