Glass Working Cutting, Grinding, and Drilling 71 



drawing this point across the surface against a steel rule. If 

 the point is not really cutting, and only tearing the surface, it 

 will probably crack the glass on overshooting the edge, so that 

 it is well to stop before actually reaching the edge, until certain 

 the instrument is cutting. With a diamond one may tell by 

 the sound when cutting is taking place, and it is only necessary 

 to ease up at the edge for the sake of the diamond. The glass 

 is severed as before. 



Cutting down broken Winchesters, etc. Fre- 

 quently broken stock bottles may be cut down to make 

 useful jars or other appliances with very little trouble. A 

 Winchester quart bottle with a broken neck, which would 

 be ordinarily discarded, may, for example, be usefully 

 employed as a jar if cut off halfway down, while a similar 

 bottle broken at the base may be used either as a rapid filter, 

 Fig- 5 9, or as a bell jar, by cutting off and grinding past the 

 broken portion. 



The method of performing this is as follows : A strip of 

 brown paper 2" wide is wound round the bottle, until three 

 thicknesses surround it immediately above the point where the 

 cut is desired, see Fig. 60. About |" away from this a similar 



-fitter paper 

 -glass 



FiG. 59. FIG. 60. Winchester quart 



bottle prepared for cut- 

 ting before the blowpipe. 



strip is wrapped, and each strip tied tightly near the inner edges 

 with string. The whole is then dipped vertically into a bucket 

 of water, until the paper is thoroughly saturated, taken out, and 

 rotated horizontally before a fairly fine blowpipe flame, arranged 

 so that the flame touches the glass between the paper strips. 

 Presently the bottle may crack round the heated circle, but, if 

 not, it should be dipped into the water once more, vertically 

 (this is important), when the crack will usually occur evenly, and 

 the lower half will fall into the water. The sharp edges 



