Hook Auger - wheelwright's  reamer 

28" hook auger or wheelwright's reamer with a 15" cutting edge,  late 18th / early 19th century with German maker's mark. Used to finish the holes in wheel hubs.  I sold a 200 year older auger - dated 1543 - about 10 years ago through a major international auction. (pic here)  It was identical apart from one major detail: it was not complete. In fact, I'm now convinced that I have never seen a complete hook auger before - only the parts. Along with everybody else I assumed the hook was there to pull the auger downwards, either with a rope or with an attached weight. No image ever showed any of this. In fact, in every major historic trade illustration  the wheel worked on is shown too close to the ground to give enough clearance for auger and weight. Looking at this tool there can be little doubt that we all got it wrong. The hook is there to attach an extension or a liner.  I assume the auger was first used without, then with the liner. Alternatively, the liner could actually have acted as some sort of a chip breaker  That would have to be tested.  Once you see the two parts joined the function of the hook is clear. There is no room for rope or weight.  Salaman under Auger, Hook, actually shows a drawing of what he calls a shell piece or liner but he too failed to make the connection.

Wim van Wingerden kindly supplied a link to  "Ambacht & Gereedschap" a Dutch tool collector's group (link here) where he found this Belgian tool catalogue from 1911, listing hook augers with and without the liners