Page:Philosophical Transactions - Volume 054.pdf/263

. I would recommend likewise an increase of their number; as the effects of one apparatus of this kind can extend only to a certain distance, and that to no great one; and the security, where mischiefs from lightning are frequent, must arise from their number. In countries and places so circumstanced, no house or other building should be without one at least; large edifices ought to have several. The number should be in proportion to the size of the building.

III. In powder magazines, I should recommend the apparatus to be detached from the building itself; and to be only placed as near it as might be. Powder magazines should never be constructed so, as to cover a large quantity of ground. If securiry from lightning was considered in their construction as a considerable object, I should recommend a circular building; in the periphery of which should be placed storehouses sufficient in their number and extent to contain the quantity of powder proposed. In the centre of this circle should be a well, very near which should be erected a pole or mast, high enough to reach some feet above the buildings of the powder magazine, or the buildings in it's neighbourhood. From this mast there should rise a brass rod, five or six feet in length, an inch in thickness, and ending in a point; and from this rod a wire of copper of a size not less than that of a large goose quill, should be conveyed down the mast, and terminate in the water of the well. If there is no well, the wire should be laid into the nearest water; as the expence even of same hundred yards of a wire of this sort can hardly be considered as an object in an affair of this