Here is the atlatl. There's a hook at one end, that you put into a notch in the dart, and at the other a weighted handle and loops to put fingers through.
Here is the atlatl loaded with one of the sixty-three inch darts, ready for throwing. The notch at the base of the dart fits onto the hook, and you use your thumb and forefinger to make "guides" so the dart stays parallel to the atlatl.
Then you swoosh it up overhand, and off goes the dart. Basically, the atlatl makes the lever of your arm longer, so you can apply more force, the same way you can hit a ball harder with a tennis raquet than you can throw one. Swoosh! (Picture of gfish, right after a throw.)
This analogy only works, though, if you regularly use a haunted tennis raquet.
See, archeologists had been digging up atlatls for years - they're found on every continent early man got to, a precursor to bow and arrow. We knew they were for spear-throwing, so people made spears out of good sturdy wood and launched them around a bit, and has such horrible results they decided the only way you could get any accuracy was if you'd been trained since you could walk to use one. Nobody knew how the Aztecs could launch darts that punched holes - front and back - through steel conquistador armor.
But things go very, very differently if you make your darts from, say, dogwood, something that bends. You load the dart onto the hook, and when you start to push the atlatl forward, you start a wave in the dart, like a ripple traveling across a pond. The ripple moves all the way down to the end of the dart, and echoes off the arrowhead, like sound, like a long low wavery C. And then the ripple rushes back towards the feathered end, your hand and the atlatl, but since you're just now nearing the top of your swing, you apply even more force, more music to it. So it echoes again, higher and louder, and bounces off the arrowhead one more time, and back to the fletching, but this time, if your timing is perfect, you're at the end of your swing; you aren't putting any more force into it to bounce the ripple back again.
So instead it jumps off the atlatl. The first time I got all the timing and motion right, I was astounded - it felt like the dart just drew a breath and came alive, a long and copper-striped snake. I didn't push it out into the air; it just flew.
The wierdest part, I think, is the aerodynamics. If you shoot a regular arrow, it "cuts" its way through the air, and the air flowing above it gets tangled up into eddies and turbulence. That's why we put feathers for fletching on arrows - it keeps the arrow's linear motion solid enough that the eddies don't just spin it uselessly end over end. Instead, if the arrow drifts a little away from horizontal, the eddies just push it back onto course. This stability is very important in archery; it's what keeps arrows flying straight.
When you're shooting a five-foot flexible dart instead of a foot-long arrow, you get the same effect, sort of. If you mess up and shoot too low, the entire dart writhes and curls in the air, pulls itself horizontal. If you fire too low, you can watch it actually bend and fly upwards. (This is incredibly spooky the first time it happens, I assure you. One wishes to grab the universe by its lapels, shake it a bit, and demand one's regular physics back.)
But, so incredibly cool! Ammunition that hums in your fingers like a wind through grass, uncurls and flies itself from the atlatl, and curves and changes direction in midair!
Oh, and can be thrown nine hundred feet. Or punch through steel armor. Twice. Or, when thrown very gently by a newbie, split wood at a great distance. This is one of gfish's throws:
So. Very. Cool. Squee!
Please note, this post does not mention a certain aluminum-edged cube, even once. This reference is too obllique to count. Nyah. :)