Dating presto canning jars
John Mason was a tinsmith in New York and perfected a machine that would cut threads into the lids, creating a jar with a reusable, screw-on lid.
This process was easier and more reliable than the tin lid and wax method.
Soldiers, too, were often left on the battlefields without proper nourishment due to the lack of food-storage solutions.
Indeed, in 1809, Napoleon offered 10,000 francs to anyone that could devise a way to...
If it's a very old model, the number can probably be found on a label attached to the top of the cover.
Old units have model numbers like 40, 50, 204, 603, etc.
Mason's 1858 patent for a fruit-canning jar expired, the brothers prepared to move into glass.