is kept tight against leakage by a spring, r, pressingagainst the end of the shaft. This spring also servesas a break to the movement of the shaft, and itspressure can be adjusted by a screw, r 1 . A counter-weight to balance the grating might be attached tothe shaft o.
To remove scum or crust from the surface of theliquid in the bath a skimmer is placed near themouth, E. It consists of a blade worked by anexternal handle, so as to push the scum along acurved plate into a small wire gauze basket, where itdrains, the basket being taken out and emptied whenit has been filled up. The liquid is kept down tothe required level by a syphon overflow pipe, u. Thebath is suspended by its upper flange on the walls ofits setting, with flue space under and around it. It isheated by the products of combustion from a fire, T,which after passing through the bath flues escape bya passage, l 3 , to the chimney, w 1 . From the fire, t,besides the passage, t 1 , to the flues of the bath governedby a damper, f, there is also a direct passage, « 2 , tothe chimney, ti 1 , with a damper, u 3 . By means ofthese dampers the heat of the bath can be easilyregulated.
The cover of the bath ismade in several parts; thefirst part, v, is hinged at i; 1to a fixed part, x, so that itcan be raised as a door, _cand there are two otherdoors, y and y 1 , the one foraccess to the scum basket,and the other for observingthe adjustment of the sole,
E, and grating, L. In the
fixed part, x, of the cover is placed a thermometertube, v, preferably close to one side of the bath; anda pipe may be connected from x to the chimney,a 1 , to carry off vapour.
For tempering glass vessels and other articles, thesole of the furnace on which the articles are placedto be heated is mounted by arms on an axis workedby an external lever. In its horizontal position thissole covers over the top of the bath, which is, more-over, closed by a sliding plate under the sole. Whenthe articles are heated sufficiently they are moved bya rake on to a narrow lateral sole, which is fixed ona level with the movable sole. The latter is thencanted to one side so as to expose the mouth of thebath, and the sliding plate being then withdrawnthe heated articles are pushed into the bath. Toprevent them from striking the sides there are fixedin the bath pieces of wire gauze inclining downwardstowards the middle, which is open, forming a sort offunnel by which the glass articles are guided downtowards the middle opening. Near the bottom ofthe bath an endless web of wire gauze is mounted onrollers, and guided by narrow rollers along its edges,and bars are fixed at intervals across it. The glassarticles are received upon this web, and when it ismoved they are carried by it upwards in a slopingdirection, and finally discharged from it at one end°f the bath into a receptacle made with a roundedVOL. II.
bottom, in which receptacle there is suspended awire gauze basket which receives them, and by meansof which they are lifted out of the bath. Immedi-ately under the sliding plate which covers the openinginto the bath below the movable sole, is mounted awire gauze rake by which the crust and scum is with-drawn from the surface of the bath before plungingthe glass articles into it. This rake is worked by anexternal handle on its spindle, and the sole is movedby an external treadle, which is connected by ratchetgearing to one of the rollers of the endless web, sothat every time the sole is moved the web is made toadvance.
Fig. 3G represents a tranverse, and fig. 37 a longi-
Fig. 38.
mmmn
a f
tudinal section ; and fig. 38 is a sectional plan of thistempering oven. The wine-glasses, tumblers, andthe like, having been previously heated in a separatestove., are introduced by the hole, a 1 , and placed uponthe sole, B, which is of stone or refractory materiallaid on a frame, b, supported by two arms, J 2 , b 2 , ona rocking shaft, C, having an arm and counterpoise, c,and an external treadle, D, by pressing down whichthe sole can be canted to the position indicated bythe dotted lines, e, fig. 36. When the sole is hori-zontal it covers the bath, and is level with a shaft, a 2 ,at the side of the bridge, a. When the articles onthe sole are properly heated they are moved by arake on to the shelf, a 2 , and then by means of thetreadle, d, the sole is canted over so as to uncoverthe bath, whereupon the articles are pushed into thebath, and the sole is returned to its horizontal posi-tion. As the sole does not form a perfectly tightcover to the bath, a sliding plate, f is arrangedunder it, the said plate being withdrawn by anexternal handle, f 1 , at the time of plunging. A6