Glass Working Exercises 



just perform the work desired, and by holding the tube in the flame 

 in such a way that the centre of the ultimate bend is in the centre 

 of the gas flame. The curve taken by a tube in bending will be 

 exactly that which can be made out of the heated portion, con- 

 sequently one generally knows beforehand the kind of curve which 

 will result. 



EXERCISE 4. From a 2o-cm. length of tubing make a U-tube, 

 having similar curves at the base, and limbs of equal length (two 

 right-angle bends, Fig. 77). 



EXERCISE 5. Bend a 20-cm. length of tubing twice, at right 

 angles in opposite directions, keeping the whole in one plane 

 (Fig. 78). 



EXERCISE 6. Bend a 20-cm. length of tubing in the form of 



FIG. 77. 



FIG. 78. 



a U at one heating. The tube must be heated in the middle for 

 about 7 or 8 cm., and smartly bent, keeping the two limbs well 

 pressed apart while finally cooling. 



EXERCISE 7. Make a " Clowes " boiling point tube. This is 

 done by first bending in opposite directions as shown in Fig. 79. 



FIG. 79. 



FIG. 80. 



Then cooling, and heating the portion A B until rather softer than 

 usual, and quickly turning the ends backward until the desired shape 

 is reached (Fig. 80). It is essential that the previous bends be 



