Just found this about the TriVelox gears on the Hetchins Brilliant. It seems that the hub is referred to as a 'splined' hub and the benefit is that you get perfect chain line in all 3 gears. Seems cool to me.

Great entry on Disraeli Gears, too:
http://www.disraeligears.co.uk/Site/...ue_-_1937.html