APPENDIX J. DATA RESPECTING THE SECTIONAL AREA OF METAL REQUISITE FOR LIGHTNING CONDUCTORS.

(N.B.—In order to avoid confusion, all areas of iron have been reduced to ?th of their actual sizes, so that virtually tables I. and II. may be regarded as giving all details for copper—but the metal is specified in each case.)

TABLE I.—LIST OF METALS MELTED.

Material	Form	Size		Remarks
		Diameter.	Area of Copper.
		in.	in.
Copper	Rod	·35	·10	Duprez, App., p. 92
Copper	Rope	·31	·075	At Nantes, Callaud’s TraitÉ, p. 89
[6]Not Specified.	Rope		·07	At Carcassone, Callaud’s TraitÉ, p. 89
Iron	Rod		·03	Harris on Thunderstorms, p. 109
Brass	Rod	·20	·03	Duprez, App., p. 92
Copper	Rod	·13?	·01?	Sullivan, App., p. 195

TABLE II.—REMARKS RESPECTING DIMENSIONS.

Material	Form	Size		Remarks
		Diameter	Area of Copper.
		in.	in.
Copper	Rod		·61	Trinity House smallest, App., p. 183
Copper	Rod	·75	·44	Will carry any flash, Harris on Thunderstorms, p. 115
Copper	Rod	·50	·20	Never yet failed, Faraday, App., p. 89
Copper	Tube		·20	War Office smallest, App., p. 70
Copper	Tape		·19	Gray & Son’s smallest, App., p.
Iron	Rod		·16	Never affected, Franklin, App., p. 52
Copper	Any form		·11	Recommended by Phin, App., p. 103
Iron	Rod		·11	More than sufficient, Gay Lussac, App., p. 58
Copper	Rope	·38	·11	Recommended by Callaud, App., p. 104
Copper	Tape		·09	Freeman & Collier’s smallest, App., p. 10
Iron	Rod		·08	Never known to be melted, Pouillet, App., p. 62
Iron	Rod		·08	Should not be less, Henry, App., p. 99
Copper	Rope	·39	·06	Carried off heavy discharge, Callaud TraitÉ, p. 89
Iron	Rod		·06	Recommended by Callaud, App., p. 104
Iron	Rod		·06	Recommended by Mohn, App., p. 107
Copper	Rod	·25	·05	Recommended by Mohn, App., p. 107
Iron	Rod		·04	Recommended by Phin, App., p. 103
Copper	Rod	·20	·03	Recommended by Zenger, App., p. 106
Iron	Rope		·02	Recommended by Mann, App., p. 108
Iron	Wire		·01	Sufficient for any house, Preece, App., p. 101

Partly extracted from the Appendix at the pages quoted, and partly compiled from specimens collected by the Conference, and from trade circulars.

Pattern	Diameter	Breadth	Thickness	Superficies	Area	Weight per foot	Remarks, and References to Appendices.
	Inches	Inches	Inch	Inches	Inch	oz.
Tube	Ext. 1½ Int. 1		¼	Ext. 4·71 Int. 3·14	·98	60	Sir W. Snow Harris (49)
Hemicylinder	1½			3·86	·88	54	Trinity House, Mains (183)
Hemicylinder	1¼			3·21	·61	37	Trinity House, Branches (183)
Tape		3	3/16	6·38	·56	34	Freeman & Collier’s largest (10)
Tube	Ext. 1½ Int. 1¼		?	Ext. 4·71 Int. 3·93	·54	33
Rod	¾			2·35	·44	27	Faraday preferred this to smaller (89)
Tape		3	?	6·25	·37	23	Gray & Son’s largest (7)
Tube	Ext. 1 Int. ¾		?	Ext. 3·14 Int. 2·36	·34	21
Tape		2	?	4·25	·25	15	Sanderson’s largest (23)
Tape		1½	·15	3·30	·23	14
Rod	½			1·57	·20	12	War Office (70) Sir W. Snow Harris (49)
Tape		1½	?	3·25	·19	12	War Office (70) “Smallest desirable” Gray & Son (7)
Tube	Ext. ? Int. ?		?	Ext. 1·96 Int. 1·18	·20	12	War Office (70)
Tape		2½	1/16	5·12	·15	9	J. Davis & Son (14)
Rope (49 square wires)	?			10·78	·15	9	Pennycook & Co.
Tape		2	1/16	4·12	·13	8
Tape		1	?	2·25	·13	8	Phin, of New York (103)
Rope (49 wires)	½			8·00?	·10	6	{Massingham (15) Newall’s Rope
Tape		1½	1/16	3·12	·09	6
Tape		¾	?	1·75	·09	6	Freeman & Collier’s smallest (10)
Tube	Ext. ? Int. 13/16		1/32	Ext. 2·75 Int. 2·55	·08	5
Rope (36 wires & hemp centre)	7/16			5·00?	·08	5	J. Davis & Son (14)
Spratt’s Patent Plait (20 wires)		1?		4·52	·08	5
Tape		1	1/16	2·12	·06	4
Rope (49 wires)	?			6·00?	·06	4	Newall’s Rope
Tape		?	1/12	1·42	·05	3	Sanderson’s smallest (23)
Spratt’s Patent Plait (14 wires)		1		3·16	·05	3
Hart’s Plait (13 copper wires and 1 zinc one)				3·08	·05	3