Use Germantown worsted, white or any desired color, with a hook large enough to carry the yarn smoothly. Commence with a chain of 140 stitches, turn.
1. Miss 3, 1 treble in each of 68 stitches following, shell of 3 trebles, 2 chain and 3 trebles in next stitch, to widen for center of back, a treble in each remaining stitch, turn.
2. Chain 3 for 1st treble, a treble in each treble, including the 3 trebles of shell, up to the 2 chain, make a shell as before under 2 chain, then a treble in each following to the end, turn. Work always in back vein of stitch to produce the ribbed or striped effect.
3 to 23. Same as 2d row. The jacket is now ready for joining.
Commencing at the point in center of back, count 26 stitches, then fold over and, starting from the other end of the same row, crochet the two sides together for 25 stitches, taking a stitch from each side. This will leave about 65 stitches for armscye.
For the border:
1. Shell of 6 trebles in a stitch, miss 2, a treble in next, miss 2; repeat. Commence with 3 chain for 1st treble of 1st shell, and join to that.
2. Shell of 6 trebles between 3d and 4th trebles of shell in previous row, and treble in treble; repeat.
3. Chain 4, fasten back in 1st stitch for a picot, a double between 2 trebles, repeat, making 5 picots around the shell, a double in single treble; repeat.
Work around the armscye in same way.