From the serial number it is a Singer 15, built in 1936. I made the assumption that the belt would have to be cut and joined again to fit my machine/table configuration. Fortunately, my husband is very handy (and handsome) and would be able to do this for me. And, it looks like they made a LOT of Singer 15s. But I am not sure how much slack there needs to be in the belt. I did a quick search on YouTube and it looks like there's plenty of help there too.
As long as it works, I don't care what it is made of.
Thanks for all the suggestions! The board is always very helpful!