Dear Peter,

I lived in Spain years ago on a study abroad program, and took a few dance classes while I was there. I've just dug my own castanets out of my instrument box...now to see if I can describe what to do to play them properly. You slip the loop (the part without the knot) onto your thumb (second joint), then you slip the second loop onto your thumb, about halfway between the joint and the thumbnail. If the knot is tied properly, you should be able to tighten it just by pulling on one of the strings (obviously, pulling on the other string will loosen it again). You want it fairly tight, so that the two halves of the castanet are apart.

Then, to play them, you can use either your middle two fingers to get a nice, solid "thwack," or, starting with your pinky finger and working your way up to your index finger, quickly touch the edge of the castanet and then curl your finger off and away (as if your fingertips were on the edge of the piano keys, and you wanted to play a descending [right hand] or ascending [left hand] scale really quickly and then get your fingers off the keys).

See if you can get some flamenco/sevillanas music to get a feel for the rhythm you want to achieve. Think red wine, impassioned glances, etc.--you get the idea.

(It's so much easier to show than to describe; I hope this gives you an idea.)

Cheers and have fun with it,

Liz