A spear-thrower, spear-throwing lever, or atlatl (pronounced or ; Nahuatl ahtlatl ) is a tool that uses leverage to achieve greater velocity in dart or javelin-throwing, and includes a bearing surface that allows the user to store energy during the throw.
It may consist of a shaft with a cup or a spur at the end that supports and propels the butt of the spear. It's usually about as long as the user's arm or forearm. The user holds the spear-thrower in one hand, gripping near the end farthest from the cup. The user puts the butt end of the spear, or dart, in the cup, or grabs the spur with the end of the spear. The spear is much longer than the thrower. The user holds the spear parallel to the spear-thrower and going in the other direction. The user can hold the spear, with the index and thumb, with the same hand as the thrower, with the other fingers. The user reaches back with the spear pointed at the target. Then they make an overhand throwing motion with the thrower while letting go of the spear with the fingers.
The dart is thrown by the action of the upper arm and wrist. The throwing arm together with the atlatl acts as a lever. The spear-thrower is a low-mass, fast-moving extension of the throwing arm, increasing the length of the lever. This extra length allows the thrower to impart force to the dart over a longer distance, thus imparting more energy and higher speeds.
Common modern ball throwers (such as molded plastic arms used for throwing tennis balls for dogs to fetch) use the same principle.
A spear-thrower is a long-range weapon and can readily impart to a projectile speeds of over .
Spear-throwers appear early in human history in several parts of the world, and have survived in use in traditional societies until the present day, as well as being revived in recent years for sporting purposes. In the United States, the Nahuatl word is often used for revived uses of spear-throwers (or the Mayan word ); in Australia, the Dharug word is used instead.
The ancient Greeks and Romans used a leather thong or loop, known as an ankule or amentum, as a spear-throwing device. The Swiss arrow is a weapon that works similarly to amentum.
Design
Spear-thrower designs may include improvements such as thong loops to fit the fingers, the use of flexible shafts or stone balance weights. Dart shafts can be made thinner and highly flexible for added power and range, the fletching can be spiralized to add spin to the dart making it more stable and accurate. Darts resemble large arrows or small spears and are typically from in length and 9 to 16 mm (3/8" to 5/8") in diameter.
Another important improvement to the spear-thrower's design was the introduction of a small weight (between 60 and 80 grams) strapped to its midsection. Some atlatlists maintain that stone weights add mass to the shaft of the device, causing resistance to acceleration when swung and resulting in a more forceful and accurate launch of the dart. Others claim that spear-thrower weights add only stability to a cast, resulting in greater accuracy.
Based on previous work done by William S. Webb, William R. Perkins claims that spear-thrower weights, commonly called "bannerstones", and characterized by a centered hole in a symmetrically shaped carved or ground stone, shaped wide and flat with a drilled hole and thus a little like a large wingnut, are an improvement to the design that created a silencing effect when swung. The use of the device would reduce the telltale "zip" of a swung atlatl to a more subtle "woof" sound that did not travel as far and was less likely to alert prey. Robert Berg's theory is that the bannerstone was carried by hunters as a spindle weight to produce string from natural fibers gathered while hunting, for the purpose of tying on fletching and hafting stone or bone points.
Woomera
The woomera or ‘miru’, allow hunters to apply more force, speed and distance when launching their spears. A woomera is usually made from Mulga wood, and serves many other purposes such as a: receptacle for mixing ochre for traditional paintings for ceremonies, deflection tool of enemies’ spears in battle, fire making saw, or a utensil for chopping game. This tool is usually long and wide, and comes in a concave, elliptical shape.
Artistic designs
Several Stone Age spear-throwers (usually now incomplete) are decorated with carvings of animals: the British Museum has a mammoth, and there is a hyena in France. Many pieces of decorated bone may have belonged to bâtons de commandement.
The Aztec atlatl was often decorated with snake designs and feathers, potentially evocative of its association with Ehecatl, the Aztec wind deity.