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An illustration of the fermentation tanks in the Barclay, Perkins and Company brewery in Park Street, Southwark. From 'London: a Pilgrimage' by Blanchard Jerrold and Gustave Doré, 1872. Jerrold writes of the process: "The boiling satisfactorily done, the wort flows out into broad lakes, airily situated - where it can become rapidly cool, without getting sour; and then it gradually subsides into these prodigious gyle tuns, about which staircases are ranged, and in which you would have to drag carefully for the body of an elephant. In these towers, against which men look like flies, the wort ferments and we have porter, or 'entire'."
© Museum of London