"This is the strongest Butt-Beer that is Brewed from brown Malt, and often sold for forty Shillings the Barrel, or six Pound the Butt out of the wholesale Cellars: The Liquor (for it is Sixpence forfeit in the London Brewhouse if the word Water is named) in the Copper designed for the first Mash, has a two Bushel Basket, or more, of the most hully Malt throw'd over it, to cover its Top and forward its Boiling; this must be made very hot, almost ready to boil, yet not so as to blister, for then it will be in too high a Heat; but as an indication of this, the foul part of the Liquor will ascend, and the Malt swell up, and then it must be parted, look'd into and felt with the Finger or back of the Hand, and if the Liquor is clear and can but be just endured, it is then enough, and the Stoker must damp his fire as soon as possible by throwing in a good Parcel of fresh Coals, and shutting his Iron vent Doors, if there are any; immediately on this they let as much cold Liquor or Water run into the Copper as will make it all of a Heat, somewhat more than Blood-warm, this they Pump over, or let it pass by a Cock into an upright wooden square Spout or Trunk, and it directly rises thro' the Holes of a false Bottom into the Malt, which is work'd by several Men with Oars for about half an Hour, and is called the first and stiff Mash: While this is doing, there is more Liquor heating in the Copper that must not be let into the mash Tun till it is very sharp, almost ready to boil, with this they Mash again, then cover it with several Baskets of Malt, and let it stand an Hour before it runs into the Under-back, which when boiled an Hour and a half with a good quantity of Hops makes this Stout. The next is Mash'd with a cooler Liquor, then a sharper, and the next Blood-warm or quite Cold; by which alternate degrees of Heat, a Quantity of small Beer is made after the Stout."You'll notice the very scientific sticking-your-finger-in method of determining if the water was hot enough for mashing. Each of the five mashes seems to be at a different temperature: a bit more than blood-warm, almost boiling, cooler, hotter, blood-warm. Sounds simple. Why did they ever bother introducing thermometers?
Here's a question for you homebrewers out there. Have any of you ever tried brewing without a thermometer? Yes, I realise it's a crazy thing to do in this modern age. But I'm intrigued as to how tricky (or not) it might be. Brewers did manage without thermometers for several thousand years, so it can't be that difficult. Can it?
Oh, and no butt jokes, please.