Carmen Martinez, age 12, of Camden, N.J., for her question:

HOW DOES A LOOM WORK?

Weaving is the process of making cloth by crossing two sets of threads over and under each other. Many fabrics and most blankets and rugs are woven on looms.

Almost all looms have the same basic features and weave fabric in much the same way. On most looms, cloth is woven on a metal or wooden frame located at the front of the loom and parallel to the floor.

The weaver must thread the loom before weaving. A set of "warp" threads is wound onto the cylinder called the warp beam at the back of the loom. The warp stretches lengthwise on a frame. The "weft" is what the crosswise threads are called and they must be repeatedly drawn over the warp. The weft is sometimes called the "woof" or the filling.

Each warp thread is passed through one of two or more vertical frames called "harnesses." Each warp is threaded through a narrow opening in one of many strings or wires called "heddles." The heddles hold the individual threads in place and prevent tangling.

Next the weaver winds the weft thread around a spool called the "bobbin." The bobbin is held in an oblong container called the shuttle. The shuttle acts as a needle that draws the weft thread over and under the warp.

The weaving process starts when the weaver lifts the harness that holds the odd numbered threads. This action creates a space called the "shed" through which the shuttle and weft thread then pass.

Finally, the weaver lowers the first harness and pushes the newly woven row into place with a device called the "beater" or "reed." The beater is in a frame, located in front of, and parallel to, the harness. It has comblike teeth made of steel wires that push each weft row compactly into place to tighten the weave.

To weave an additional row, the weaver raises the second harness and passes the shuttle through the shed. The weaving of each row involves the same process.

The finished cloth is wound around a bar called the "apron beam," or "cloth beam," at the front of the loom.

There are two basic types of looms: hand looms and power looms. A hand loom is any loom that is not power driven, such as a table loom or a floor loom.

Historians don't know when the process of weaving cloth developed. But civilizations in central Europe, the Middle East and Pakistan probably learned to weave textiles by 2500 B.C. Ancient wall paintings illustrate weaving techniques mastered by the Egyptians as early as 5000 B.C.

The Chinese learned to weave sometime between 2500 and 1200 B.C. They became famous for their spinning silk thread that was woven into exquisite brocade and damask fabrics in Syria and Persia, which is now Iran.

The Pueblo and other Indian tribes of what is now the Southwestern United States started to weave cotton textiles during the A.D. 700s.