Glass Working Exercises 91 



As a rule, students use the blower much too freely, and 

 pass far too much air through the flame, cooling it unduly, and 

 preventing the formation of a well-shaped flame. The blower 

 should be worked with gentle and gradual strokes, rather than in 

 rapid puffs, and the flame produced should have a pointed tip, 

 and be practically silent. Opening the control cock will 

 convert such a flame into a cooler, larger, and broader flame, 

 suitable for warming a piece of glass to the required tempera- 

 ture for working, or cooling off (annealing) a piece already 

 worked this without any difference in the pressure upon the 

 air sent through the flame. Closing the control cock, con- 

 versely, will produce a fine pointed flame, very hot, and suitable 

 for heating one special spot in a tube without unduly heating 

 the surrounding glass. Thus all flames required can be obtained 

 by the use of a gentle current of air. 



It may be noted here also that it is necessary for students 

 to acquire the ability to work the blower quite independently 

 of any movement of the hand ; and the not unusual picture of 

 foot, arm and head moving in unison should never be seen 

 after the first few hours' work at the blowpipe. In order to 

 help in the attainment of this freedom of action, it is well to 

 practise independent movement while away from the blowpipe. 

 Take a pen-holder, for example, and holding it between the 

 thumb and fingers of the right hand, roll it completely round 

 on a horizontal axis, never varying its position in space ; then, 

 having acquired some dexterity in this occupation, continue 

 the motion while adding the movement of the right foot such 

 as would be made use of in manipulating the blower. 



Dexterity in these particulars will be found of the utmost 

 service in handling glass, and will well repay time spent away 

 from the blowpipe in their acquirement. The flame of the 

 blowpipe is fixed, and it is of the utmost importance that the 

 glass-blower should be able to rotate his glass, and thus heat it 

 evenly, while keeping it at one particular point in the flame. 

 Should the glass leave the flame during any part of its rota- 

 tion, one portion of it will be cooler than the rest, and will 

 therefore not respond as readily to whatever subsequent treat- 

 ment the glass is subjected, an uneven result being produced, 



