The use of iron chains as conductors gave rise to very many fatal accidents, and for a time resulted in an outcry that the system itself could not be depended upon, as it was known to be not always efficacious. Lists were published of numerous instances in which buildings with what were supposed to be the best conductors were struck by lightning, from which it was argued that Franklin’s great discovery of the electric force always seeking a metallic path to the earth was a myth. It was not till some painstaking scientific men, deeply interested in the subject, had set to work to discover the causes of the failure, that the whole became plain enough. The chains, in some of the instances in which they had proved inefficient lightning conductors, were found to be corroded to such an extent as barely to hang together. Of course this corrosion would impair the efficiency of the conductor by reducing the quantity of metal; but the chief objection to the use of chains lies in the fact long ago pointed out by Mr. Newall, that even supposing a chain were formed of links of half-inch copper rods, and were perfectly bright and clean, the area of the conductor is reduced to a mere point where the links touch each other, and the resistance becomes so great in such a small conductor that instances have been recorded of the fusion of the links. In other cases, as in that of H.M.S. ‘Ætna’ in 1830, the chain was boomed out, and did not touch the water! Simultaneously with the chains, there was trial made, in several Continental states, and also in England, of several other metallic conductors besides iron. Tin and lead had both their advocates, but the latter more than the former, on account of its far lower price. As regards tin, it had really no advantages whatever over iron, except pliability and non-oxidation. Against this was to be set that it was much more expensive than iron, with only about the same conducting power, according to Becquerel, Ohm, and other investigators. Professor Lenz, it is true, ranked tin very much higher, asserting, from experiments of his own, that its power of conductivity was nearly twice that of iron; and it was partly owing to his great influence that the metal obtained a trial in several countries, more particularly in Russia and in the United States of America. Still, the result was not satisfactory on many accounts, and its price alone brought tin to be soon abandoned as a conductor. Lead had a far longer trial. Its cheapness recommended it strongly, and equally so its extreme pliability. One of the greatest difficulties of the constructors of ‘Franklin rods,’ when first they came into demand, was to make the iron pieces fit properly around sharp corners of buildings, either by bending them in fire, or, as was more commonly done, soldering them together, or employing screws and other joints. But it was early discovered that these junctions, when occurring at acute angles, were