228 Prof. Perry on Long -Distance Telephony, 



Another way of putting the results in these tables is 

 this : — Let K be the whole capacity of the line in farads, 

 R its resistance in ohms, L its whole self-induction in 

 secohms, S the w T hole leakage-conduct! vity in mhos : L/R 

 and S/K are the same as the l/r and s/k of the tables. For 

 given values of these find the number in either table ; square 

 it and divide by any chosen m 2 or n 2 ; this gives the product 

 of the whole capacity K and the whole resistance R of the 

 conductor. 



Of course in all lines which have the same values of L/R 

 and S/K, the product KR is constant. 1 must again draw 

 attention to the fact that we have neglected the terminal con- 

 ditions. 



I have not hitherto said anything about the amplitude of 

 the current ; in fact the receiving apparatus has been sup- 

 posed to be infinitely delicate. It is obvious that 1/h is the 

 distance in which the amplitude becomes l/e th of its initial 

 amount. If the numbers in the following Table V. be divided 

 by s/hr for any line, they give the distances in which a cur- 

 rent of frequency 955 per second has its amplitude halved. 



Table Y. 



Values 

 of s/Jc. 



Values of - X 10 5 . 

 r 







1-667 



16-67 



50 



83-3 



116-7 



1667 





 215-4 



430-8 

 861-5 

 1723 

 3015 

 4308 

 6462 

 8616 

 10770 



•0127 

 •0124 

 •0122 

 •0118 

 •0110 

 •0099 

 •0091 

 •0079 

 •0071 

 •0065 



•0167 

 0130 

 •0128 

 •0123 

 •0114 

 •0102 

 •0093 



•0197 

 •0188 

 •0177 

 •0167 

 •0145 

 •0121 

 •0105 



•0314 

 •0283 

 •0257 

 •0218 

 •0166 

 •0124 

 •0100 



•0402 

 •0340 

 •0295 

 •0233 

 •0164 

 •0115 

 •0090 



•0476 

 •0389 

 ■0315 

 •0236 

 •0158 

 •0106 

 •0081 



•0567 

 •0331 

 •0329 

 •0232 

 •0147 

 •0096 

 •0072 



The effect of leakage is in every case to diminish the ampli- 

 tude of the current, making it necessary to have more sensitive 

 receiving-instruments or more powerful sending-instruments. 



If some of our clever mathematicians would for a while 

 put aside the ambition to write original papers and would 



