My little Lorch-Schmidt lathe now up and running!

[Yorkie]

Yes, that's one way of looking at the 'other' jaws, although they're usually used to grip the outside of bar stock like in my picture. The ones you have are usually used to grip bar stock that is too large to go down the centre hole of the chuck or the spindle.
Your lathe is usually used with collets, and they turn up regularly on eBay. You'd better make a nice comb jointed box for them - See Col for a suitable brass plate
Alan

I've found a second set of jaws, and have added a couple of pics below. As you'll see from the profile of two of them, they look as though they're meant to grip tubular stock internally. I've also added a pic of the box of collets and other bits and bobs, and the gizmo that fits in place of the tailstock into which the collets fit. The levered handle can be moved to the left to drill stock in the chuck. I'm sure that it will have a proper name, but I don't know what it's called. I haven't yet fettled it up - it's a bit scruffy! The box seems to be original. There's also a pic of the collet holder and a collet before fitting to the levered gizmo.

I put Colin's nameplate exercise in the same pigeon-hole as my 'cube in a cube in a cube', and a number of other things in life - the only time that you feel like doing it twice is just before you've done it once! I tend to be a bit tempestuous, and lacking the patience needed for intricate time consuming tasks, even though the end result is rewarding, and always a 'conversation piece'.

Hope the pics are of interest.

David