The report on the protection of the Louvre Palace did not contain the last inquiry of the ‘Académie des Sciences’ on the subject of lightning conductors. Twelve years after it had been issued, the Government of France once again called upon that learned body for advice as to the best mode of protecting powder magazines. Several cases had happened--among others at Rocroy, on the borders of the forest of Ardennes--of such buildings being struck, notwithstanding that they had conductors placed upon them, and the Government, naturally alarmed, made inquiry as to whether nothing could be done to ensure protection against lightning, infallible under all atmospheric conditions and every possible emergency, to these dangerous stores. The demand was made in a letter of the Minister of War, Marshal Vaillant, dated October 27, 1866, pressing the ‘Académie’ to give another ‘Instruction,’ without delay, the Government being ‘in fear that some of the powder magazines are not as completely protected from lightning as could be wished.’ Thereupon the ‘Académie des Sciences’ nominated another commission, this time of eight members, including the Minister of War himself--not complimentary, but as being an author, and with a warm interest in electrical science; and, besides him, MM. Becquerel Sen., Babinet, Duhamel, Fizeau, Edmond Becquerel, Regnault, and Professor Pouillet. The list represented a galaxy of names unsurpassed in the investigation of such a subject as lightning conductors, looked upon in most countries of Europe, at least in recent years, as rather plebeian, to be left to builders and lightning rod men. Many sittings were held by the committee, all fully attended, so that, although the Minister had desired to get the new report ‘_le plus promptement possible_,’ it was not till nearly three months after the receipt of his message that it was completed, Professor Pouillet again being the author. It was a most remarkable paper, this one, read before and approved of by the ‘Académie des Sciences’ on January 14, 1867.