It is indeed desirable for various reasons that the copper rope or band forming the lightning conductor should be affixed to the building in the neatest and least obtrusive manner possible. The conductor may be fastened by means of ordinary metal staples made of stout copper wire. A better method however is indicated in figs. 31 and 32, one showing the rope conductor formed of forty-nine wires, usually employed by Messrs. R. S. Newall and Co. for the protection of ordinary houses and buildings, and the other the copper band used by them for the same purpose. This fastening is simply a strap of copper bent to the required shape and pierced with two holes, by means of which it is fixed to any building by copper nails or screws. This method possesses several advantages; it is very sightly and neat, it can be easily applied without injury to any building, and as it allows the conductor a certain freedom of movement, it readily permits the contraction and expansion caused by the variations of temperature. The band conductor shown here is one inch wide by one-eighth of an inch thick, and weighs ·44 pound per foot. The rope conductor, although it appears less, has more metal in it; it measures five-eighths of an inch in diameter, and weighs ·67 pound. Fig. 33 shows a different mode of attaching the lightning conductor. It is generally used for the heavier ropes. Fig. 34 exhibits an apparatus called a ‘tightening screw.’ It is used for making the conductor taut when it gets loose from any cause. The diagram explains itself, so there is no necessity for describing it. The tall chimney shafts of factories and similar buildings, from which smoke or rarefied air escapes, are peculiarly liable to be struck by lightning. This is principally due to the current of smoke or warmed air forming, with the soot in the chimney, a medium conductor leading to the iron-work of the furnace or stove beneath, but ending there--a result that must be carefully avoided; for although a conductor that leads past any object is a protection (provided always that it has a good earth connection), a conductor that leads to an object, and ends in that object, is a distinct danger. It is therefore necessary to offer to the electric discharge a better conductor, able to intercept it and convey it safely to earth on the outside of the shaft. [Illustration: Fig. 34.] [Illustration: Fig. 35.]