Off to the left side of the dining table shown in image 18211 is a storage unit which has a butter churn on it. (Just before another clotheshorse with the outfit of a housewife of the period hanging on it.)

In this device, cream was stirred vigorously up and down via the wooden plunger until it began to turn to butter... about an hour later. It's amazing that 18th century women didn't have forearms like Schwarzenegger. (Of course, it's possible that some of them did.)

A pleasant side-effect of the process was buttermilk, which was quite a popular drink at the time.