320 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



a set of curves that will be more selective than the wireless-telegraph 

 curves, and we can in this way fix a limit to the sharpness of resonance 

 that can be attained in practice. Some computations of this character 

 on the extent to which interference can be prevented under certain 

 conditions, assumed as practical, have been published elsewhere.^ 



LO 



.8 



.6 



.2 

 .1 



.4 .6 .8 



Xa/X 



1.0 L2 1.4 1.8 L8 



Figure 11. Resonance curves obtained by tuning with Circuit III while 

 Circuit IV is at best value. t = .30, 774 = 1. 



VIII. The Maximum Current, and Detector Resistance. 



Equation (23) is an expression for the maximum current that can be 

 obtained in Circuit IV, when the inductances and capacities of Circuits 

 III and IV are given their best values. 



An interesting fact that can be obtained from an examination of 

 equation (23) is that the square of the current multiplied by Hi gives 

 a quantity independent of B^. This means that the heat developed in 

 Circuit IV is independent of M4 ; that is to say, the same amount of 

 heat is developed in Circuit IV, at best resonance, whether a liigh- 

 resistance or a low-resistance detector is employed. This means that, 

 if the detector is an instrument for measuring heat, a low-resistance 

 detector would be as sensitive as a high-resistance detector if it were 

 not for the fact that the lower the resistance of the detector the less 

 the proportion of the total heat that is developed in the detector itself, 



* Pierce, Principles of Wireless Telegraphy, McGraw-Hill Book Company, 

 New York, 1910. 



