. Spons' dictionary of engineering, civil, mechanical, military, and naval; with technical terms in French, German, Italian, and Spanish . rinding surfaces. The grinding 1670 GLASS MACHINEEY. motion being thus obtained, sand and water are constantly applied, until the surface of the glass isfound upon examination to be free from all defects ; the sand is then washed off the glass, and thefirst stage of the smoothing process is commenced on the same machine by substituting the coarserqualities of emery in place of the sand. The plate of glass is then removed from the bench,turned over, and repl
. Spons' dictionary of engineering, civil, mechanical, military, and naval; with technical terms in French, German, Italian, and Spanish . rinding surfaces. The grinding 1670 GLASS MACHINEEY. motion being thus obtained, sand and water are constantly applied, until the surface of the glass isfound upon examination to be free from all defects ; the sand is then washed off the glass, and thefirst stage of the smoothing process is commenced on the same machine by substituting the coarserqualities of emery in place of the sand. The plate of glass is then removed from the bench,turned over, and replaced on the bench, and submitted to the same process on the other side. Thespeed at which the fly-frame is driven is about forty revolutions per minute. It will be seen thatthe runner-frame B, ÌFig. 3238, is not sufl&ciently large to act upon the entire surface of a largeplate of glass at one time ; it is therefore necessary to divide the operation and shift the position ofthe runner-frame as the work requires it, by inserting the centre stud of the rimner-frame into adifférent portion of the slot between the ñy-frame bars Until the last few years the principal part of the operation of smoothing was effected by manuallabour, the operation being performed by rubbing two pieces of glass together, and applyingemery powder between them. Great care is requisite as the work approaches completion that noscratching shall take place ; and it is on this account that hand labour is considered absolutelynecessary for finishing the process, the slightest scratch being immediately felt by a practised hand,whilst a single stray particle of grit on a machine would spoil the whole surface before it wasperceived. About 1857 Crossley introduced a machine for smoothing the plates of glass,which so far succeeded that the nicety of the hand touch is only required for the final part ofthe operation. This smoothing machine, shown in plan in Fig. 3239, is exceedingly simple andinexpensive, consi
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Keywords: ., bookcentury1800, bookdecade1870, bookidsp, booksubjectengineering
