Government that well-constructed lightning conductors had failed to do their duty. For a length of time these reports were either not believed in, or the failure ascribed to partial non-compliance with the strict rules laid down by the ‘Académie des Sciences.’ However, in the end, when thirty years had passed, the instances of buildings with conductors being struck became so numerous, that it was impossible to ignore them any longer and, flying once more for advice to the savants of the ‘Académie des Sciences,’ the French Government desired them to investigate anew the question as to the best means of protecting buildings against lightning. Complying with the behest, the learned body nominated again a committee of six, the names of those selected comprising the most eminent men who had made electricity and its phenomena their study. They were MM. Becquerel, Babinet, Duhamel, Despretz, Cagnard de Latour, and Pouillet. The ‘Instruction’ of the new committee, drawn up by Professor Pouillet, was read before the ‘Académie des Sciences’ on December 18, 1854, and having been unanimously approved, was, like the former one, taken up by the Government and extensively circulated. The report began by modestly excusing the short-coming of its predecessor. ‘For the last thirty years,’ Professor Pouillet remarked, with no fear of being gainsaid, ‘the science of electricity has made great progress--in 1823 the discovery of electro-magnetism had only just been made, and none could foresee the immense results that would spring from its revelations.’ Based upon these grounds, the new ‘Instruction’ entirely reversed many of the conclusions of the old one. First of all, it declared inadmissible the theory of a fixed area of protection, to be calculated by the length of the upper rod. ‘Such a rule,’ Professor Pouillet justly remarked, ‘cannot be laid down with any pretence to accuracy, since the extent of the area of protection is dependent from a mass of circumstances--such as, among others, the shape of the building and the materials entering into its construction. It is clear, for example, that the radius within which the conductor gives protection cannot be so great for an edifice the roof or upper part of which contains large quantities of metals, as for one which has nothing but bricks, wood, or tiles.’ Professor Pouillet then proceeded to give detailed instructions in respect to the design and mode of manufacturing lightning conductors. He insisted that the rods should be of greater capacity than those recommended by Gay-Lussac in the report of 1823, and that there should be as few joints as possible from the point to the earth. He considered it of the greatest importance that all the joints should be carefully tin soldered, otherwise the metallic continuity of the conductor could not be assured. He also advised that the top of the air-terminal should not taper to so fine a point as formerly, but be rather blunt.