This original silk crepe mourning cap dates from the 1830's to early 1840's. It resembles caps for which patterns are given in The Workwomans Guide, published in 1838. There is a poufed area at the top of the back section to accommodate the tall topknot hairdos of the era.
Here you can see the extra space in the cap back. The narrow (7/16 inch) black silk ribbon covers the raw edge of the join between the cap and the edge frill.
This shows the long running stitches that keep the raw edges of the frill together. These were originally covered by the ribbon.
You can see here the sheerness of the silk crepe. The brown tape is similar to twill tape but is a plain weave and appears to have an extremely fine-gauge wire woven into both edges. It's possible that the materials that appear brown may have originally been black but have faded over time. Note the double frill layer at the sides.
Showing placement of the decorative ties that are stitched on with large, uneven stitches, using the same medium-weight thread used in the rest of the construction. The crepe is sewn to the brown tape rather than to the other sections of crepe.
The ties on this bonnet were meant to hang decoratively, not tie, They are made from a 7/8 inch wide ribbed ribbon with very narrow satin edging. The remaining length, including the area that has unraveled is 12 inches.
