For those readers who may have forgotten what a thumb drum looks like. About 8.5 by 7 inches. The graduated strips which one plucks with one's thumbs are, I think, made from nails recovered from the shacks of missionaries. At least, the best ones are.
Retired civil servant and former allotment holder from leafy Epsom. Currently geek, still interested in consciousness. Why is it not just an epiphenomenon?