US Patent 2,607,979, granted to Waldo G. Throop of Pasadena, California, for a hand loom of the square or rectangular pin-frame type. The loom has an adjustable top rail that compensates for the shortening of the yarn strands as weaving progresses, so the frame can be much larger than the traditional six to eight inch pin looms. Three variants are described: screw collar adjustment, spring-loaded automatic adjustment, and a tongue-and-slot clamp. The patent includes six drawings, a description, six claims, and a list of references cited.