I have no idea how old this thing is...about all I can say is old. It was an antique the first time I ever saw it, and the first time I ever saw it, I was a toddler.
I ain't gonna say how old I am, but suffice it to say that the birthday cake presented to me yesterday did not have any candles on it due to fire code regulations. Lets just say I was a toddler a long ass time ago and leave it at that.
Anyways, see that "2" stamped on there? I am guessing that means it holds two gallons.
I noticed that this churn has a perfectly round hollow in the bottom of it. I cleaned it up and looked at it closely and realized that the hollow had no glaze in it, while the rest of the churn did. (it is shiny in the picture down below because it got wet when I washed it out and there is water in the hole) I am thinking that hollow was worn down by whatever was holding the crosspiece on the dasher. It does not look like it was part of the deliberate design of the jar, so I am thinking it was worn there by years of use.
The way this thing worked was you simply dumped some cold cream in there, dropped in the dasher, fitted the lid, and then sat down for a long session of whipping the dasher around in the cream. That's it. You just froth the cream around and it will turn into whipped cream, getting harder and harder to churn. The whipped cream will get stiffer and stiffer and then all of a sudden it will start liquefying again and start sloshing around as the milkfat starts separating from the whey. Keep going and what you will have is clots of butter sticking to the crock and the dasher and floating in the remaining buttermilk.
There is no mystery here. You can do this, as I do, in the kitchen with a bread machine (should have a butter function or simply a knead function. Either should work.). You can use a mixer (I tried using a blender once, results not awesome with that.). My dad used to make butter using an old mason jar. Just put the cream in and shake till it throws the milkfat.
Then you pour strain out the buttermilk and rinse the butter in cold water. Rinse well, as the remaining buttermilk can make it go rancid more quickly. Blot dry and maybe mix it up with a little salt, if you like salted butter.
You can then press the butter into a mold (I even have a pretty stamp to put on mine) or just scoop it into a bowl.