﻿of Electricity on Iron Wires. 



437 





1st Maximum. 



2nd Maximum. 



3rd Maximum. 



4th Maximum. 



Cu. 



Fe. 



Diff. 



Cu. 



306 

 300 



Fe. 



301 

 294 



Diff. 



5 



6 



Cu. 



562-5 



552 



Fe. 



553 



540 



Diff. 



9-5 

 12 



Cu. 



818 

 799 



Fe. 



805 

 784 



Diff. 



13 

 15 



Upper pair... 

 Lower pair... 



45 

 40 



425 

 37-5 



2-5 

 2-5 



The successive differences should be in the ratio of I, 3, 5, 

 7, if the theory of the present investigation is correct. The 

 differences for the first two maxima are very small, so that 

 the experimental error in their determination would be 

 relatively large, and in the case of the fourth maximum the 

 damping was so great that it was difficult to fix the point 

 with certainty. The difference for the third maximum was 

 relatively large and the determination of the point was sharp. 

 Taking this difference as a point of reference, the calculated 

 and observed values are shown in the accompanying table : — 





1st Maximum. 



2nd Maximum. 



3rd Maximum. 



4th Maximum. 



Calcu- 

 lated. 



Ob- 

 served. 



Calcu- 

 lated. 



Ob- 

 served. 



Calcu- 

 lated. 



Ob- 

 served. 



Calcu- 

 lated. 



Ob- 

 served. 



Upper pair... 

 Lower pair... 



19 

 24 



2-5 

 25 



5-7 



7-2 



5 

 6 



9-5 

 12 



9-5 

 12 



133 

 16-8 



13 

 15 



The observed half wave-lengths for the four wires are : — 



{Copper (diameter 0*1201 centim.) 255*6 centim. 

 Iron ( „ 0*1186 centim.) 251*6 centim. 



{ 



Copper ( 

 Iron ( 



0*07836 centim.; 

 0*07850 centime 



251*6 centim. 

 246*8 centim. 



The wires in each pair were as near the same diameter as 

 could be found, the iron of the larger pair having slightly 

 the smaller diameter, but the copper being the smaller one in 

 the second case. In other respects the circuits compared were 

 as nearly identical as possible. The capacity per unit length 

 being the same for wires of the same diameter, the shortening 



