the loop, which creates the shed and countershed. Rigid heddles Rigid heddles are generally used on single-shaft looms. Odd warp threads go through the slots, and even ones through the circular holes, or vice-versa. The shed is formed by lifting the heddle, and the countershed by depressing it. The warp threads in the slots stay where they are, and the once in the circular holes are pulled back and forth. A single rigid heddle can hold all the warp threads, though sometimes multiple rigid heddles are used. Treadles may be used to drive the rigid heddle up and down. Multiple heddles Rigid heddles (above) are called "rigid" to distinguish them from string and metal heddles, where each warp thread has its own heddle, which has an eye at each end and one in the middle for the warp thread. The eyes in the ends are fastened to a shaft, all in a row. This requires multiple shafts; it cannot be done on a single-shaft loom. The different shafts (also called harnesses) must be controlled by some mechanism. While non-rigid heddles generally mean that two shafts are needed even for a plain tabby weave, twill weaves require three or more (depending on the type of twill), and more complex figured weaves require still more harnesses. Treadle-controlled looms Treadle looms can control multiple harnessess with multiple treadles. The weaver selects which harnesses are engaged with their feet. One treadle may be connected to more than one harness, and any number of treadles can be engaged at once, meaning that the number of different sheds that can be selected is two to the power of the number of treadles. Eight is a large but reasonable number of treadles, giving a maximum of 28=256 sheds (some of which will not have enough threads on one side to be useful). The weaver must remember the sequence of treadling needed to produce the pattern. Figure harness and the drawloom A drawloom is for weaving figured cloth. In a drawloom, a "figure harness" is used to control each warp thread separately, allowing very complex patterns. A drawloom requires two operators, the weaver, and an assistant called a "drawboy" to manage the figure harness. The earliest confirmed drawloom fabrics come from the State of Chu and date c. 400 BC. Some scholars speculate an independent invention in ancient Syria, since drawloom fabrics found in Dura-Europas are thought to