Counting Glass

a magnifying glass used for the purpose of counting the threads in the warp or woof of woven fabrics. The magnifying glass or lens, usually small, is fixed in a small frame which is hinged to an upright. The upright is in turn hinged to a footpiece in which there is a square opening, one-fourth of an inch to an inch square. The three pieces of the instrument can thus be folded together and carried in the pocket. By the aid of the glass, it is an easy matter to count the number of threads crossing the square. The glass for counting threads in linen is called a Belfast linen prover.