Hormell — Dielectric Constant of Paraffins. 437 







Table I. 











2d node with 







1st node. 



2d node. 



balance tube. 



3d node. 



4th node 



27-65 cm 



58-85 crn 



58-15 cm 



89-25 cm 



120-75° 



27-65 



58-95 



58-00 



89-55 



120-45 



27-80 



59-15 



58-30 



89-50 



120-65 



27-75 



58-75 



58-00 



89-50 



120-55 



27-80 



59-00 



58-20 



89-25 



121-00 



27-80 



58-80 



58-20 



89-60 



120-80 



27-90 



59-15 



58-35 



89-55 



120-80 



27-70 



59-15 



58-15 



89-40 



120-50 



28-00 



58-60 



58-10 



8955 



120-30 



27-95 59-00 58-00 89-75 120-50 



27-80 58-94 58-14 89'49 120*60 



is no greater. Generally a careful adjustment of the three 

 spark gaps will lead to a more brilliant and a more con- 

 stant glow of the tube. Frequently for various reasons the 

 tube will cease to glow in the dark. If on these occasions 

 white light from an incandescent lamp or a lighted match 

 be permitted to fall on the tube, it will instantly begin to 

 glow. This is no doubt " the effect of ultra violet light 

 upon the electric discharge " which Hertz* has so thoroughly 

 investigated. 



Positive and negative surgings start at the middle of the 

 first bridge and meet in opposite phases at the middle of 

 the second bridge, thus forming, according to Hertz, poten- 

 tial loops at points midway between the two bridges and 

 potential nodes at the middle of the bridges. The distance 

 between the middle points of the bridges is a half wave 

 length, the value of which can be found by adding the dis- 

 tance between the two wires to the scale reading. It is 

 doubtful just what this bridge correction ought to be, but the 

 determination of the wave length by another method (given 

 later) seems to confirm the above correction. 



This half wave is not the length of a free half wave along 

 the wires. The presence of the tube has added capacity to the 

 wires and thereby shortened the wave. The tube correction 

 must therefore be determined. To do this find the position 

 of the second node. The table shows this to be 58 - 94 cm . 



Kow place a tube, which we shall call the balance tube, in 

 contact with the wires at the middle of the second potential 

 loop. The wave is now shortened by an amount which is 

 equal to the tube effect. The balance tube ought to be of the 

 same diameter as the argon tube, but its length is not essential 



* Electric Waves, p. 63. 



