18 232.585 77.52833 .232585 .04405 .0042995 .0128985 4.2995 22.7014 19 170.879 56.95966 .170879 .032363 .0058521 .0175563 5.8521 30.8991 20 149.3915 49.797166 .1493915 .022475 .00842703 .02528109 8.42703 44.4947 21 99.195 33.065 .099195 .018787 .01008110 .03024348 10.08116 53.2285 22 75.9461 25.315366 .0759461 .014384 .0131672 .0395016 13.1672 69.5230 23 60.54377 20.181256 .06054377 .011467 .0165170 .0495510 16.5170 87.2096 24 46.8851 15.628356 .0468851 .0088798 .02132874 .06398622 21.32874 112.616 25 38.748 12.916 .038748 .0073386 .025808 .077424 25.808 136.265 26 31.3859 10.461966 .0313859 .0059443 .03186144 .09558432 31.86144 168.229 27 24.79873 8.266243 .02479873 .0046967 .0403246 .1209738 40.3246 212.914 28 18.98653 6.328843 .01898653 .0035959 .05266892 .15800676 52.66892 278.092 29 16.3710 5.4570 .0163710 .0031006 .0610834 .1832502 61.0834 322.521 30 13.9493 4.649766 .0139493 .0026419 .07168825 .21506475 71.68825 378.514 RESISTANCE & WEIGHT B.W.G Ohms Lbs. No. per lb. per Ohm. 0000 .000080272 12457.5 000 .000104529 9566.7 00 .000163553 6114.24 0 .000255196 3918.58 1 .00042102 2375.18 2 .00052422 1907.59 3 .00075786 1319.50 4 .0010629 940.844 5 .0014558 686.911 6 .0020082 497.96 7 .00324863 307.822 8 .00460101 217.343 9 .00710791 140.689 10 .0105772 94.543 11 .0164462 60.842 12 .0241593 41.392 13 .0418692 23.8839 14 .0718583 13.9163 15 .126788 7.8872 16 .191045 5.2344 17 .301355 3.31835 18 .59157 1.6904 19 1.09596 .912445 20 2.27254 .44003 21 3.25229 .30748 22 5.54843 .18023 23 8.73035 .11454 24 14.5579 .068691 25 21.3142 .046917 26 32.4863 .030782 27 52.0367 .019217 28 88.7724 .011265 29 119.404 .008375 30 164.4762 .0060804 PURE COPPER weighs 555 lbs. per cubic foot. The Resistance of 1 mil. foot at 60° Fahr. is, according to Dr. Matthiessen, 10.32311 ohms. Upon these data the above Table has been calculated. The _Resistance_ of Copper varies with the temperature about 0.38 per cent. per degree Centigrade, or 0.21 per cent. per degree Fahrenheit.