At any rate, these little pots, which only hold about a cup, were then adapted and manufactured in the English potteries.
Many Victorian examples were larger, brown and with the figure of a squirrel on top.
As you can see, there is no lid. Yet it pours out liquid.
Inside, an inverted funnel shape is the key. The wide part of the funnel is part of the base; the small opening is at the top.
To fill, turn the pot over (be sure to stop the end of the spout with your finger) and fill with liquid. Turn it right side up again by gently laying it on it's side and inverting. (The side-turn keeps the hole at the top of the funnel clear, although a few drops may escape.)
The liquid that was poured into the top when the vessel is inverted will pool into the bottom of the pot. The liquid cannot rise higher than the top of the funnel-opening. The pot can be filled as high as the inside funnel and up part of the spout. The bottom of the spout is located rather low on the pot for this reason.
For the potter, they are easier to make than you would think. The trick is to make the inner funnel first, then pull the outer walls of the form up around it, leaving the inner cavity fat at the bottom and closing the vessel in at the top. The spout is attached just the same as with a regular teapot, but you must smooth the inner seam without being able to see it.
Here's one I made and (hopefully) it will be accepted into a show coming up.