666 On the Velocity of .Electric Waves along Wires. 



1299*2 cm. and 663*4 cm. for the lower and upper curves 

 respectively. 



Diameter of Wire *. 



Wave-length. 



Proportional 

 Wave-length. 



•076 cm. (03 inch) 



1299-2 cm. 



100 



•0377 „ (-015 „ ) 



12956 „ 



99-73 



•0149 „ (006 „ ) 



12891 „ 



99-2 



•0038 „ (-0015 „ ) 



1280-5 „ 



98-6 



•0740 cm. (-03 inch) 



663-4 cm. 



100 



■0371 „ (015 ,.. ) 



660-8 „ 



99-6 



•0148 „ (-006 „ ) 



657-6 „ 



99-1 



•0036 „ (-0015 „ ) 



6516 „ 



98-2 



o — . 



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O J- 



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Fig. 



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'0075 -015 '0225 OS 



Diameter of Wire in inches. 



The effect of increasing the specific resistance of the material 

 of the wire was shown by comparing the wave-lengths, cor- 

 responding to the same frequency, along wires of the same 

 diameter but of different material. The comparison was 

 made between platinum and copper, the specific resistances 

 of which are in the ratio of 7 : 1 approximately. The fre- 

 quency was about the same as the higher of the two given 

 for the copper wires of various diameters. There was a 

 decided difference between the two wave-lengths, the mea- 

 surements of which are given below. In the determination 



* The diameters given in inches were the original diameters of the 

 wires ; these were slightly changed by stretching. 



