Attenuation Constant 024 -028 029 030 034 "030 -034 ‘036 ‘037 043 Characteristic Impedance 446 385 369 364 361 IQI 155 148 145 144 \ 26°46" | \14°52" | \9°36' \7°8" | \ 27°39" | \15°38" | \10°9’ 1X 7°30" | \ WILLIAM SPENCE ROBERTSON, PH.D. / Railways: Tracklaying. Professor of History, 1924, P. W. Wilson