Since Loganne and Brittany chose to cover 19th century books the bibliography of the books differs from the bibliography of books of today. They looked at books that had the original leather binding and could see evidence of stab stitching. In older books, the ridges you see in the spine binding, are from the pieces of thread used in stab stitching as shown in the last picture. There weren’t any obvious chain-lines, even with shining a light to the pages. A few had areas where you could see little pieces of thread from when paper was still made from torn pieces of fabric. They even found one book, An Appeal in Favor by Lydia Child, whose original leather binding on the spine has almost completely fallen off (as shown above in the second picture).
Images on this page curtesy of Special Collections, Moffett Library, Midwestern State University. Photographs taken by Loganne Featherstone and Brittany Williams.