Game on Daval! (good one!)
That mill is a working mill, and the flour that they make is used over in the village's restaurant. This year the wheel was being repaired because of ice damage sustained over the winter.
Next door to the mill is a cooper shop, where the cooper explained to me that a firkin is a barrel which holds 9 gallons.
Here's a link to a site that has almost the same pic as I took:
http://www.toronto.com/attractions/listing/000-100-039