I collect antique and vintage baseball equipment and see old rule books on eBay fairly often. They can also be found at antique shops and shows and such.
And I can't get the phrase "steam welded kapok" out of my head, either!
One thing I found strange was the photo in the book of the poor Java villagers, sitting on the dirt floor of their grass hut, hulling kapok pods by hand. Hard to imagine a time when this would be considered a selling point for any product.
It's kind of like Nike taking out an ad playing up the fact that their shoes are proudly produced by under-age workers in a dreary Malaysian sweatshop.
In honor of our 1930's softball rule book, here is a 1930's softball glove from my collection. Better use two hands!