He has 2 pictures. The top one, a forked stick with 2 rubber bands with a small pouch in the middle is the traditional slingshot. I'm pretty sure that this is what Mark Twain has in his books. I made a couple dozen of these when I was a kid.
The 2nd picture is what we call a 'wrist rocket' - basically it's a slingshot (ie. it IS a slingshot), but has a strap or brace that goes over the lower forearm to help steady the slingshot during aiming. It's used in exactly the same manner that a sling is used on a rifle. Pretty much any discount sporting goods store (eg. Wal-Mart) carries these.
What you describe is a 'sling' - ala what David used to stun Goliath in the Bible Note: he did not kill Goliath with the sling as popularly believed - he used Goliath's own sword for the cue-de-gra (sp?). Bonus points if you can tell me why he (David) picked up 5 stones instead of just 1...
