LIGHTNING RODS.
A report of one of the committees read at the recent convention of the National Fire Protection association was devoted to the subject of lightning rods. It was as follows:
The committee on lightning gave detailed specifications for the protection of buildings, such protection being specially advisable on country buildings, isolated structures and on all buildings, wherever located, having elevated features, such as tall chimneys, steeples, high peaked or gable roofs and flagpoles. One rod, with proper air and earth terminal, is recommended for each 3,600 square feet of metal roof area, and for each 1,600 square feet of roof area, when not of metal, all metal to be connected with the rod. The rod may be of iron or copper, weighing not less than two and a quarter pounds per foot, and, if of iron, to be thoroughly galvanised. It should be as straight as possible; be thoroughly grounded; and the air terminal should be not less than three-quarterinch in diameter, with the point cone shaped and the height of the cone equal to the radius of the base. One foot below the point there should be a casting holding four copper points, each six inches long and one-quarter-inch in diameter, or a group of points may be placed on the end of the terminal.
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