Faraday to George Buchanan   Between 1848 and 1850¹

The rod may be close along the brick or stone than a half-inch, it makes no difference. There will be no need of rod on each side of the building, but let the cast-iron hoop and the others you speak of be connected with the rod, and it will be in those places at least, as if there were rods on every side of the chimney.

A three-fourth rod is no doubt better than a half-inch, and, except for expense, I like it better. But a half-inch has never yet failed. A rod at Coutt’s brewery has been put up 1½ inch diameter; but they did not mind the expense. The Nelson Column in London has a half-inch rod – three-fourths is better.

I do not know of any case of harm from hoop-iron inclosed in the building, but if not in connection with the conductor I should not like it; even then it might cause harm if the lightning took the end furthest from the conductor.