From the Victoria and Albert Museum Web site.
According to the Victoria and Albert Museus, this is of, "Watered silk, lined with silk, trimmed with silk braid, and running stitches, canvas, wood and pleated." Like later rainwear, this has an under section with buttons and an over section that appears to have no attachment devices, unlike later garments. It also has a built-in hood, all in high-visibility school bus yellow.
Keywords: French, hood, straps, vest, high neckline, ruching, buttons, jacket, elbow length close upper-sleeves, lower-sleeves, peplum, Brunswick, hoodie