840 Mr. R. T. Lattey on the Dielectric 



were used as receiving inductances (L l5 L 2 ). These were 

 connected to two adjustable condensers, the other plates 

 of which were connected to two circles of brass strip (L 3 , L 4 ) 

 also in parallel with one another. Between these two 

 lay two turns of thick copper wire connected to a thermal 

 converter and a millivoltineter. 



It was found that with this arrangement the resistance for 

 high-frequency currents in the principal receiving circuit 

 was about 1/5 ohm. It is probable that this is not, properly 

 speaking, the real " resistance," but a function of this, 

 of the mutual inductance between the two circuits and 

 various leakage effects. All of these will vary when the 

 frequency is changed. The various values of K found at 

 various times were used to calculate R, and the results are 

 shown in Table VI. 







Table VI. 











X (metres) ... 



.. 33-2 



35-5 



392 



45-5 



45-5 



45*5 



45-5 



R (ohms) 



.. -306 



•269 



•346 



•211 



•210 



•216 



•206 



X (metres) ... 



.. 45*5 



45*5 



45-7 



457 



46-2 



47-3 





R (ohms) 



.. '209 



•190 



•220 



•200 



•192 



•230 





These agree fairly well with the empirical formula 

 RX=9"68. Experiments with other circuits over a wider 

 range of wave-lengths showed that this formula is ius- 

 tillable. 



The condenser used in these experiments consisted of 

 two coaxial cylinders ; the inner one could be withdrawn 

 from inside the outer by means of a screw. Mr. E. W. 

 B. Gill kindly calibrated this condenser for me with air 

 between the plates. It was connected to C by two stiff 

 parallel wires, in order that the inductance of the leads 

 might be constant. Experiments with water and with 

 glycerol in the condenser enabled a series of values of 

 pH and p 2 l r to be found ; these were in satisfactory agree- 

 ment with / = 343 cm. and l ± = 67 cm., assuming the 

 dielectric constant of water to be constant over the range 

 of frequencies employed. This assumption is justified by 

 series of experiments to be described later (see Section 

 VIII.). 



Table VII. gives the results obtained for water at various 

 wave-lengths (A.) and various temperatures. These have 



