(34) 



small inner bore if we except nos. 12 and 13 where the soldering 

 was ineffective. Helped by the experience made we have treated 

 the following tubes more carefully. With the tubes which have burst 

 under a too low pressure the existence of irregular tensions appears 

 clearly from the way of bursting, where the break has a transverse 

 or irregular direction and not, as theory requires, parallel to the axis. 



2. Maximum strain of glass threads. 



The diameter of the threads lies between 0.1 and 0.6 mm. The 

 results are combined in the two following tables. The bore was 

 determined by a measurement of the diameter in two directions at 

 right angles. The mean of these two measurements is given in the 

 tables. The first table contains the results obtained with glass threads 

 which have undergone only the operation mentioned sub § 2. To 

 investigate the influence of irregularities which thus may remain in 

 the structure of the glass we have made a series of measurements 

 by means of threads which had beforehand been heated to incan- 

 descence and then cooled very slowly. The results of this series are 

 combined in table III. 



Except the thread for which T m is lowest viz. 14.7 all the threads 

 of table II show where broken a sharply ridged structure while 

 we find at the edge a small semicircular smooth spot as was found 

 by Winkelmann and Schott- 1 ). 



i) p. 718 loc. cit. 



