---------------------------+----------+---------+---------+ Area in square inches | 0·25 | 0·5 | 1·0 | Area in square millimetres | 161·25 | 322·5 | 645 | Weight of copper in lb. | | | | per 100 yards | 576 | 1153 | 2306 | Cost of copper at | | | | 7¾_d._ per lb. | £18 15 0| 37 5 0| 74 10 0| Laying | 9 0 0| 9 12 0| 9 12 0| Insulators | 0 4 6| 0 4 6| 0 4 6| 6 surface boxes and | | | | connections | 10 0 0| 10 0 0| 10 0 0| Culvert, 18 inches × | | | | 12 inches, for | | | | two lines conductor, | | | | in brickwork | 53 8 0| 53 8 0| 53 8 0| and cement, replacing | | | | pavement | | | | Engineers and | | | | superintendence | 6 0 0| 10 0 0| 10 0 0| +----------+---------+---------+ Total | £97 7 6|120 9 6|157 14 6| Extra for copper at | | | | 9½_d._ per lb. | 3 5 0| 8 10 0| 17 0 0| +----------+---------+---------+ Total |£100 12 6|128 19 6|174 14 6| Cost of copper per lb. | | | | laid complete | 42_d._ | 27_d._ | 18·2_d._| Current in ampères | 90 | 180 | 360 | Cost per ampère | 1 2 3| 0 14 5| 0 9 8| ---------------------------+----------+---------+---------+