This section is from the book "School Needlework. A Course of Study in Sewing designed for use in Schools", by Olive C. Hapgood. Also available from Amazon: School Needlework: A Course Of Study In Sewing Designed For Use In Schools.
2. Holding the wrong side of the cloth towards you, insert the needle from the right side, two or three threads from the end of the opening.
3. Holding the right sides together, overhand the gusset to the cloth, as far as the crease or point b (Fig. 50); fasten securely.
4. Overhand the other side in the same manner, beginning at point a.
Fig. 50. - Showing the gusset folded over.
5. Fold the gusset over on the crease.
Fig. 51. - Showing the middle of the gusset pinned, and the finished gusset on the wrong side,
Fig. 52. - Showing the finished gusset or the right side.
7. Baste and hem the gusset to the cloth.
8. Make a row of stitching at the fold of the gusset, to strengthen it (Fig. 51).
Fig. 53. - Showing other ways of cutting a gusset.
The gusset can be made as large or small as desired; it can also be cut in different shapes (Fig. 53). An easy method of inserting a gusset is to cut a small square of cloth; fold and crease the edges; placing a corner at the end of the opening, overhand two sides; fold on the bias and hem the remaining sides over the over-handing stitches.