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BELL SYSTEM TECHNICAL JOURNAL 



the lines for which the observations were made appear in Fig. 1. With 

 the exception of one rubber insulated line all inner conductors were 

 supported on porcelain insulators. The latter were attached to the 

 inner conductor by means of spring clips, extruded metal ears or by 

 means of soldered rings. Some measurements were made on lines 

 assembled with soldered joints and some on lines connected by means 



COPPER. /0= 2 19x103 



INSULATOR DESIGN 



COPPER:/o = 1 74X10^ 

 P^= 201x103 



INSULATOR DESIGN 



SPACED 4 FT 



SPACED4FT 



COPPER: /o= 203x103 



INSULATOR DESIGN 

 (o) f THICK 

 SPACED 18' 



.527" 

 COPPER: /o z1.74Alo3 



INSULATOR DESIGN 

 (o)j"THICK 

 SPACED 12" 



F"ig. 1 — ^Principal dimensions of the concentric tube lines upon which the experimental 

 resistance measurements shown in Fig. 2 were made. 



Line E — Same dimensions as "C." Brass (p = 6.6 X 10') outer pipe. 



Line F — Same dimensions as "C." All brass (p = 6.6 X 10'), insulators spaced 

 22 inches. 



Line G — -Same as "C" but filled with insulators. 



Line if— Lead sheath cable, No. 18 B & S copper (p = 1.7 X lO'), rubber insula- 

 tion, lead (p = 17 X 10') j-inch inside diameter. 



Line I — Same as "C" but insulators spaced 9 inches. 



Line J — Same as "F" but insulators spaced 18 inches. 



of pipe unions with miniature plug and jack connections for the inner 

 pipe. Various line lengths were employed. Most of the observations 

 comprised measurements of the quantity (i?/2 + GZq^/2). The 

 measurement procedure will be described later. 



