Two double welt pocket samplers which my grandmother, a dressmaker, sewed in 1951. Both samplers are made with thin wool fabric.
The welt pockets are sewn by machine, and the raw edges are finished by hand.
Here are 1916 instructions about how to sew a herrinbone or catch stitch.
Here’s a tutorial about how to sew a double welt pocket, and another tutorial for a double welt pocket with a flap.
Here’s part 9 (handsewn square neckline) and part 11 (trapunto quilting) of the 1950s sewing and embroidery series.