296 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



gives a maximum of current. We shall call the condenser capacity 

 that gives a maximum of current the " resonant C4 " for a given C^. 

 In seeking an expression for the condition for resonance, it is to be no- 

 ticed that, as Cz has been diminished, the value of the "receiving 

 capacity " C4 required for resonance has been increased (compare 



24 



Cli 



1 20 



bjDlS 



« 

 v 



"812 



§10 



'S 

 « 8 



t 6 



10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 

 Receiving Capacity 



Figure 4. Relation of height of Antenna to C4 for resonance. 



Curves 1 to 7). On passing to a smaller length of antenna, in the 

 neighborhood of 11.8 meters, the value of C^ for resonance became very 

 great and the amount of current received became inappreciably small. 

 With this length of antenna, 11.8 meters, the condition of the receiving 

 circuit was at its worst, for upon further decreasing the length of an- 

 tenna to 10.5 meters resonance reappeared in the form of Curve 8. 

 The resonance relation had undergone a discontinuity and the capacity 

 C4 for resonance had jumped back toward the origin. Now, decreasing 

 the length of the antenna further to 10, 9, 8, and 7 meters successively, 

 I obtained the resonance curves 9, 10, 11, and 12 respectively ^ of 

 Fiijure 3. 



^ Curves 9 to 12 are plotted magnified about five times in comparison 

 with Curves 1 to 8. In examining these curves it should be borne in mind 

 that the decrease of length or height of the receiving antenna carries with it 

 a double effect; namely, (1) a decrease of reach of the antenna into the field 

 of force, and (2) a shift of the resonance relations of the receiving station with 

 respect to the incident waves. We are at present concerned only with the 

 second of these effects. 



