While fermentation continues, the same vigilance which prevails in every part of the brewery, must be constantly exercised. The conversion of sugar into alcohol and carbonic acid gas should be gradual, not sudden; hence, when the fermenting process becomes too rapid, either by reason of defective yeast or on account of the unsuitable temperature, it must be restrained by means of attemperators, that is, coils which are placed in the fermenting-tun and connected with the refrigerating plant. As in all other operations thus far described, so here, too, the prolific genius of our age of inventions has placed at the command of the brewer machineries with which he can regulate the temperature of these oceans of turbulent, foaming liquids, either by a light pressure of his hand, by the turning of a small wheel, by pressing upon a knob, or by such other equally simple manipulation. In this fermenting room, as well as in the cellars, into which we shall pass presently, everything assumes Titanic proportions, and the human beings who move about these places appear like pigmies. When we see fermenting-tuns holding from three hundred to four hundred barrels, and settling tuns of the size of an ordinary house, extending through two stories, and holding seven hundred barrels or twenty-one thousand seven hundred gallons of beer; and when we consider that these monster casks, filled with John Barleycorn’s blood, cover miles upon miles of cellar-room, we begin to realize and appreciate the power of the engines which are at work in this brewery. As fermentation progresses, workmen are constantly in attendance to watch the process. On ladders, almost three times the size of their own bodies, they climb to the top of the tuns to skim the beer with huge ladles, testing at the same time, by taste and touch, the condition of the liquid mass, in order to determine when to draw it off to the resting-tuns. The transfer of the beer from the fermentation vats to the resting-tuns and from these to the storage casks is accomplished by hydraulic and air pressure, and in such a way as to require no other labor but that of opening or closing valves or depressing levers. As we descend into the cellars, three stories under the ground, the temperature becomes more and more stinging, the walls and ceiling are covered with ice to the depth of from three to five inches, and every vat and cask is thickly encrusted with frost. In forming an idea of the capacity of these cellars, we cannot simply depend upon the number of square feet of ground occupied by them, because both vats and casks rise to a height almost equal to that of the cellars, and they vary in capacity from fifty to five hundred barrels. The beer contained in them would float a fleet, since their aggregate minimum capacity amounts to 125,000 barrels. [Sidenote: FINAL OPERATIONS]