These are long stitches used to compress a length of fabric before
sewing it to a shorter piece. To gather, set the machine for a long
stitch length (3.0-4.0 mm; use the shorter length for lighter-weight
fabrics) and loosen the tension slightly. With the fabric right side up,
sew on the seamline and again 1⁄8" (3 mm) from the seamline, within the
seam allowance. Sometimes you will be instructed to place the first
line of stitches 1⁄8" (3 mm) from the seamline within the body of the
garment so the stitches don't become tangled in the permanent seamline.
Leave thread tails at each end and do not backtack. Pin the fabric to be
gathered to the shorter piece right sides together, matching edges,
centers, and pattern markings as directed in the pattern. Pin at each
mark. Grasp the bobbin threads from both lines of stitching at one end
and pull gently. Work the gathers along the thread until the entire
piece is gathered and lies flat against the shorter fabric piece. Pull
the bobbin threads from both ends to gather long pieces. Stitch the
seam, then remove the gathering threads.