Cool, I have one of those as well. Mine is also a 1797. What a coincidence. Those 1796s are really hard to come by I hear.
Steve has the definition that I'm familiar with. At least as I remember, the term "Cartwheel" was used by my Grandfather when talking about some Two Pence coins he had. I have never seen anything larger come out of the UK. For what ever that is worth.