Note 5 — Chapter I · On the Intimate Relation existing between the Deterioration of Beer, or the Wort from which it is Made, and the Process of Brewing.
Frank Faulkner translation
In some breweries (at Lyons especially) fermentation at a high temperature is practised in large vats at about 15° C. (59° F.). The yeast which covers the surface of the liquid is skimmed off and stored in flat tubs.