The last line looks like it says "ten gallons of water is a good quantity". But that's the prpblem with really old cookbooks. The recipes were more of a reminder of what was in it. You were supposed to know how much of what as a good cook or brewer. I hate that part,it's really frustrating.
Interesting that ale became beer when you boiled it to add hops. Ale could be no more than 4 days fermented when ready to drink. Wow,that had to be borderline nastie. Not to mention the waste of a lot more grain than our modern processes use. Just mash,cool,add yeast culture,& ferment 4 days. It was thought to be alive,beer was dead. How bout that??
Also, for the record, "Ale, Beer, and Brewsters in England" is a good book, with good information about medieval brewing culture, but it is very much written from a feminist perspective. I would still recommend though if any one is curious.
Fermenter 1 - Centennial Pale Ale
Fermenter 2 - Nothing
Bottle conditioning - Nothing
Drinking - Oatmeal Stout