Note 6 — APPENDIX J. DATA RESPECTING THE SECTIONAL AREA OF METAL REQUISITE FOR LIGHTNING CONDUCTORS.
Reading edition
Assumed to have been Iron, the dimension given is “18 mm.” = ·70 in. diam., or ·38 in. area.
Reading edition
Assumed to have been Iron, the dimension given is “18 mm.” = ·70 in. diam., or ·38 in. area.