Art and Picture Collection, The New York Public Library. “Front pleats on dress with stitched bodice detail” New York Public Library Digital Collections. Accessed April 1, 2016. http://digitalcollections.nypl.org/items/8007f9e0-aa6a-0132-4b82-58d385a7b928
Last night I did a little reading about pleats, also called plaits. Both words have the same meaning and are derived from the Latin plicare, to fold. I learned there are three kinds of pleats: side , box or inverted . Side pleats fold to one side. A pleat is three thicknesses of fabric. Plaits can be edge stitched. They can be fastened to tape on the inside to help control them. Two rows of gathering threads can be run around the top edge if they are not stitched in place, to keep it neat until the garment is fully assembled I imagine.
More specific advice about pleats in skirts can be found in the booklet “Tailored Garments”, published by Woman’s Institute of Domestic Arts and Sciences in 1931. Full view at the url below. Two skirts are described in this booklet. Making The Skirt begins on page 46. The first skirt is a two piece pattern that has a pleat in each side seam. If you want to add pleats (or plaits) to a plain two piece pattern, the instructions are to “add 2 to 2 1/2 inches beyond the seam line at each side, both front and back, for the plaits.” That might be 2 inches divided by 3 for the width of the plait.
The second skirt is part of “A Boyish Tailleur” (a tailleur is defined as a woman’s tailor made suit) which begins on page 52. The suit has a one piece wrap around skirt. Instructions include how to plan it out without using a pattern and how to make French tacks to hold side flap closed.
The scans below are from the 1921 edition of “Tailored Skirts” by the same publisher and show finishing details for the three types of plaits: side, inverted and box.
The photo illustration of 1921 is recycled in the 1931 booklet. Here is shown how to finish the two piece skirt with side pleats.
1921 edition, Inverted Plait Skirt, next two scans
1921 edition, Box Plaited Skirt