Twentieth century hand-book for steam engineers and electricians, with questions and answers .. . FIGURE 12. 26 ELECTRICITY FOR ENGINEERS quarter-circle from one adjacent corner to the otheradjacent corner, the area inscribed by the compasswould again be .7854 of a square inch. The above will explain to the reader the relation. figure 13, between the circular and square mil. The circularmil is a circle one mil (-joVo °f an inch) in square mil is a square one mil long on each the calculation of wires for electrical purposes, thecircular mil is generally used, because we nee

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Twentieth century hand-book for steam engineers and electricians, with questions and answers .. . FIGURE 12. 26 ELECTRICITY FOR ENGINEERS quarter-circle from one adjacent corner to the otheradjacent corner, the area inscribed by the compasswould again be .7854 of a square inch. The above will explain to the reader the relation. figure 13, between the circular and square mil. The circularmil is a circle one mil (-joVo °f an inch) in square mil is a square one mil long on each the calculation of wires for electrical purposes, thecircular mil is generally used, because we need onlymultiply the diameter of a wire byitself to obtain its area in circularmils. If we used square mils weshould have to multiply by .7854. The resistance of a conductor(wire) increases directly as its length,and decreases directly as its diameteris increased. A wire having a diam-eter of one mil and being one footlong has a resistance at ordinary temperature of If this wire were two feet long, it would have

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