Most of the experiments and investigations for ascertaining the best form of lightning conductors, and their application to buildings so as to be invariably efficient, have been carried on by private activity; still, the subject has also, at various times, undergone the examination of official authorities, as well as of learned societies. Little has been done in this respect in England, but very much in France, where, ever since the publication of Franklin’s great discovery, the question of protection against lightning has uniformly interested the public, as well as the learned world, leading to the production of more treatises on the subject than in any other country, except perhaps Germany, the world’s centre of book-making. One of the most important of the French works here referred to, and which may be regarded as the standard work on lightning conductors, is a semi-official publication, entitled ‘Instruction sur les paratonnerres,’ issued in new editions from time to time, and widely dispersed, not only in France, but all over Europe and America. It consists of several reports about lightning conductors made, from 1823 to 1867, by committees comprising some of the most distinguished men of science at the time, to the ‘Académie des Sciences’ of Paris. The earliest of these reports originated from an application of the French Government to the ‘Académie.’ In the year 1822, there happened to be in France, and over the greater part of Continental Europe, an extraordinary number of violent thunderstorms, accompanied by earthquakes and simultaneous eruptions of Mount Vesuvius, the latter on a scale not witnessed for centuries. In France, the almost continuous thunderstorms caused great alarm among the population; and the priests in many places held processions in and around the churches, with special prayer-meetings, to ‘appease the wrath of heaven.’ In consequence of all this excitement, the Minister of the Interior, deeming that something also ought to be done besides the walking in procession to stay the fatal effect of lightning, ordered that all the public buildings in France should be protected immediately by conductors, made on the most perfect model and placed in the best manner. To get pre-eminent advice as to the efficiency of lightning conductors, the Minister applied officially to the ‘Académie des Sciences,’ which learned body thereupon nominated a committee consisting of six of the most celebrated investigators of the phenomena of electricity--MM. Poisson, Lefèvre-Gineau, Girard, Dulong, Fresnel, and Gay-Lussac. The committee held many sittings, collecting a vast amount of evidence on the subject, and on April 23, 1823, presented through M. Gay-Lussac its report to the ‘Académie des Sciences,’ which was adopted and ordered to be printed, being declared a highly important document. The French Government took the same view as the ‘Académie des Sciences,’ and not only acted upon the recommendations