I got a few of these pics out of an old book called A Textbook of Horseshoeing for horseshoers and veterinarians by Lungwits and Adams, published in 1966. It is a piece of rope jammed into a shoe packed with some kind of tar to hold it in. It was for traction on roads if I remember right. There was a couple different kinds. Let me see if I can find the other pics.
