122

BEEK.

rouser, which carries round a chain hung in loops, to prevent the hops from adhering tothe bottom of the boiler. Three bent stays,/, are stretched across the interior, to supportthe shaft by a collet at their middle junction. The shaft carries at its upper end a bevel

wheel, g, working into a bevel pinion upon the axis ft, which may be turned either bypower or by hand. The rouser shaft may be lifted by means of the chain i, which, goingover two pulleys, has its end passed round the wheel and axle ft, and is turned by awinch : l is a tube for conveying the waste steam into the chimney m.

The heat is applied as follows:—For heating the colossal coppers of the London breweries, two separate fires are required, which are separated by a narrow wall ofbrickwork, n,figs. 107, 108. The dotted circle a' a' indicates the largest circumference ofthe copper, and b' b' its bottom; o o are the grates upon which the coals are thrown,not through folding doors (as of old), but through a short slanting iron hopper, shown atp,fig. 107, built in the wall, and kept constantly filled with the fuel, in order to excludethe air. Thus the lower stratum of coals gets ignited before it reaches the grate. Abovethe hopper p, a narrow channel is provided for the admission of atmospherical air, insuch quantity merely as may be requisite to complete the combustion of the smoke of• the coals. Behind each grate there is a fire-bridge, r, which reflects the flame upwards,and causes it to play upon the bottom of the copper. The burnt air then passes roundthe copper in a semicircular flue, s s, from which it flows off into the chimney m, onwhose under end a sliding damper-plate, t, is placed for tempering the draught. Whencold air is admitted at this orifice, the combustion of the fuel is immediately checked.There is, besides, another slide-plate at the entrance of the slanting flue into the verticalchimney, for regulating the play of the flame under and around the copper. If the platet be opened, and the other plate shut, the power of the fire is suspended, as it ought tobe, at the time of emptying the copper. Immediately over the grate is a brick arch, «> toprotect the front edge of the copper from the first impulsion of the flame. The chim-ney is supported upon iron pillars, v, v; w is a cavity closed with a slide-plate, throughwhich the ashes may be taken out from behind, by means of a long iron hook.

Fig- 109 represents one of the sluice-cocks, which are used to make the commu-nications of the pipes with the pumps, or other parts of the brewery, n b representsthe pipe in which the cock is placed. The two parts of this pipe are screwed to theside of a box, c c, in which a slider, A, rises and falls, and intercepts, at pleasure, thepassage of the pipe. The slider is moved by the rod a. This passes through a stuffing-