The atlatl works like the plastic ball launcher you use to throw for your dog
A spear-thrower is a stick about as long as a forearm with a hook or cup at the far end. Seat a long dart against it, swing overhand, and the extra leverage sends the dart far faster than an arm alone. Lacrosse sticks, jai alai baskets and dog-ball launchers all run on the same trick.
The thrower grips one end, rests the dart along the shaft with its butt against the spur or cup, and holds the dart lightly with thumb and forefinger. Reaching back with the point aimed at the target, the user whips the upper arm and wrist forward and releases. The device acts as a light, fast extension of the arm, lengthening the lever so that force is applied to the dart over a longer arc, which means more energy and more speed.
Such tools appeared early in human history on several continents and remain in use in some traditional societies, and they have been revived as a sport. In the Americas people often borrow the Nahuatl word atlatl or the Mayan hul'che; Australians say woomera, from the Dharug language. Greeks and Romans used a leather loop called an amentum or ankule, and in New Caledonia a cord wound around the dart, which French colonists called a doigtier, set it spinning.
How fast does it really go? Tests with replicas of Basketmaker-era throwers, measured by radar guns, chronographs and high-speed film, put the top launch speed at 72 to 108 kilometres per hour, and claims of 160 or more probably reflect faulty measurement. A 25-pound self bow shoots arrows at about 129, and a replica Catawba bow reaches 160. Yet the heavy darts carry more momentum, 1.8 to 2.7 kilogram-metres per second against 1.5 for the Catawba arrow.
Darts typically run 1.2 to 2.7 metres long, and refinements include finger loops, flexible shafts and spiral fletching for spin. Many throwers carried stone weights of 60 to 80 grams, called bannerstones, shaped a little like big wingnuts. Their purpose is argued: extra power, steadier aim, or, as William Perkins suggests, muffling the swing's zip into a quieter woof less likely to startle game. Robert Berg thinks hunters used them as spindle weights for spinning cord.
Source: Spear-thrower
