The terminal rod of the conductor generally projects about four feet above the chimney or other highest point of the building. It consists of a round iron rod seven-sixteenths of an inch in diameter, the lower extremity being hammered out for the purpose of fastening it to the conductor by soldering and screws or by bolts. A small building, not exceeding twenty-five feet in length or breadth, is generally fitted with either one terminal rod placed on the centre of the ridge of the roof, or with two rods, one at each end of the ridge, the latter method being the preferable one. In larger buildings terminal rods are placed at intervals of about twenty feet along the roof. The upper end of the rod is sometimes pointed, but not always, the argument being that although the ordinary end of a rod is blunt when used in connection with a Leyden jar, but that when applied to a thunder-cloud, which extends over thousands of acres, it becomes pointed, and bears the same proportion to a thunder-cloud as the sharp point of a needle does to the hand of a man. Occasionally the point is tipped with platinum, gold, silver, or pure copper, in order to prevent oxidation, but this is not considered essential, it being presumed that, practically no amount of rust on the top would impair the efficacy of the terminal rod. In the case of a building having a flag-staff upon it, a galvanised iron wire is fastened along it and projects about six inches above the top, the lower end of the wire being of course carefully soldered or otherwise connected with the main conductor. Steeples and spires, in addition to the ordinary vertical conductor, are fitted with horizontal conductors placed around them at intervals of about twenty feet, and connected with the vertical conductor. This is to provide against the occasional discharges that take place in the centre of steeples, and which are caused by the deflection of the discharge in the air by the rain.