Roff
Greenie
My buddy and I have found several of these at old homestead sites. They appear to be bottle necks, but for what?
Almost. This made me think of water bags. When I was a kid, we had one hanging on the front bumper when we went on long trips. The bag was made of canvas, so it oozed water. Evaporation kept the contents cool, even on a hot day. You had to stop to get a drink. It doubled as radiator backup water, which was sometimes needed on a hot day, especially if you had some long uphill grinds. I found one with Google Images that looks like a match.For a canteen?