86 Trans. Acad. Sci. of St. Louis. 



were not obtained, sueli as were obtained by the arrange- 

 ment first described, and which was used later. 



One end of each wire was then fixed to a glass tube by 

 means of sealing wax. Switching connections were so 

 made that alternate and equal discharges from either 

 terminal could be sent into one wire at the free, and the 

 other wire at the fixed end, and thence to ground. The 

 other teniiinal of the machine was gi'ounded on a separate 

 earth connection. 



Precisely the same buckling effects were obtained as in 

 the former arrangement. These effects were alike from 

 end to end of each wire. The last half-centimeter at the 

 fixed end showed the same effects as the last half-centi- 

 meter at the free end. This also points to balanced longi- 

 tudinal stresses within the wire as the cause of this buck- 

 ling effect. The irregularity in form may be due to va- 

 riations in structure and foiTa of the drawn wire. In a 

 previous paper, such waves in a fine platinum wire were 

 described, and their form was much more nearly uniform. 

 That some differences in the length and form of striae 

 in a vacuum tube are observed, is well known. 



Added June 17, 1912. 



After this paper was in type, a simple method sug- 

 gested itself, of practically eliminating opposing end 

 thrusts due to point discharges from the ends of the wire 

 in the device of Fig. 1. About 1 cm. of the wire at each 

 end was bent downwards at right angles to the wire. 

 This results in applying these end thrusts at right angles 

 to the direction in which the wire creeps. This effect is 

 thus also utilized in diminishing frictional contact be- 

 tween the wire and the edge of the glass at the ends of 

 the tube. The ends of the wire rise slightly as the con- 

 ditions for the disruptive discharge are approached. The 

 effect of thus directing the ends of the wire downwards, 

 is to slightly increase this upward lifting of the wire at 

 its ends. It does not appear to materially increase the 



