LIGHTNING PROTECTION.

LIGHTNING PROTECTION.

State Fire Marshall H. D. Davis, of Ohio, has devoted considerable time to the consideration of the subject of protection against lightning. He has embodied his investigations as follows: The Standard Rod.—Protection against lightning is advisable on isolated buildings, and on all buildings having tall chimneys, steeples, high-peaked or gable-roofs, or flagpoles. One “rod’ with proper air and earth-terminal is recommended per unit of roof-area, as follows: Pitched roofs of metal, one each 2,000 square feet of ground area; pitched roofs other than metal, one each 5,000 square feet ot ground area; flat roofs of metal, one each 5,000 square feet of ground area. Air-terminals should never be more than Fifty feet apart and each should be provided with its individual ground. A low, broad building of greater area than seventy-live by too feet ean best be protected by an additional rod through the centre of the building. Air-Terminals.—The air-terminal is to be placed at the highest point of the rxif or structure, Where there are two or more gables, or other projections above the roof, of nearly equal height, each to have an air-terminal, and all to be connected together. Where trees stand so close to a building that branches overhang, or approach very close to the roof, a conductor, with proper earth terminal to extend along the trunk of each tree to near tile highest branch top fastened by a baud round the branch or trunk, and equipped with a cluster of points. Conductors. Conductors to be put in sheet or tape form of either copper, weight not less than six ounces per foot, or iron weighing not less than two and one-quarter pounds per foot, the latter to be painted or galvanised to prevent corrosion. One-inch iron rod can be used to connect iron ground witli copper conductor, the conductor terminating above the surface of the ground. Air-terminals to be rods of iron or copper, not less than tnrec-quarter-inch in diameter, with point cone-shaped and height of cone equal to the radius of the base. One foot below the point there should be a casting holding four copper points. Large chimneys should have a band of iron or copper, not smaller than the conductor, round the top six incites below the corbeling, and provided with copper points a foot long and one-half an inch in diameter. Terminals can be satisfactorily made of three-quarter inch copper or iron pipe. Joints. All joints to be made mechanically and electrically secure and then soldered. To be run down side of building where best ground is obtainable, preferably on the side most exposed to rain. Not to be run nearer than five feet to interior piping, unless absolutely unavoidable. To be run as straight as possible, avoiding all turns of radius of less than one foot, and to incline downwards throughout its entire course. Should never be insulated, but fastened securely to the surface. Must never be run through iron pipes. Connections.—Connections to be made with iron piping or castings, to be made by screwing a brass plug into same and fastening conductor securely to it, then soldering. Or, with copper ground, by riveting and soldering, the connection then being coated witti asphaltmn paint. A copper plate not less than two feet by three feet by one-sixteenth-inch buried in permanently damp earth not less than four feet below the surface, with three inches of crushed coke or charcoal underneath, and the same material above to w ithin six inches of the surface of the ground. Or. an iron casting so shaped as to have a number of pockets or cups facing upwards. Should have not less than six square feet of surface. Should be buried with not less than six inches of scrap metal and coke under and six inches over same. A proper ground is absolutely essential and permanently damp earth is absolutely required.

Canisteo, N. Y.. is bringing suit against Hornellsville, N. Y., for alleged pollution of its waiter supply by sewages discharged into the river.

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