Materials: No. 20 crochet cotton, a No. 4? crochet hook, a piece of linen. Abbreviations: Ch-chain; tr-treble; dc-double crochet; sc-single crochet. Note: Instead of being worked on a chain base, the edging may be worked into the hemmed edge of the linen. In this case, begin at the 2nd round, working 2 ch, 1 tr all around, making about five spaces to an inch. February 18, 1952. (Photo by Langham Studio).