[25] See Anderson, Lightning Conductors, pp. 170-5. [26] The Thunderstorm, pp. 158-9. See also an account of four persons who were struck on the Matterhorn, in July, 1869, all of whom were hurt, and none killed: Whymper’s Scrambles Among the Alps, pp. 414, 415. [27] See Philosophical Transactions of the Royal Society, 1773, p. 42, and 1778, part i., p. 232; Anderson’s Lightning Conductors, pp. 40-2; Lighting Rod Conference, pp. 76-9. [28] See A Lecture on Thunderstorms, by Professor Tait of Edinburgh, published in Nature, vol. xxii., p. 365. [29] Report of the Lightning Rod Conference, p. 4. [30] The dimensions here set forth are greater in some respects than those “recommended as a minimum” in the report of the Lightning Rod Conference, page 6. But it will be observed by those who consult the report that the minimum recommended is just the size which, in the preceding paragraph of the report, is said to have been actually melted by a flash of lightning; and, therefore, it seems not to be a very safe minimum. It will be also seen that there is some confusion in the figures given, and that they contradict one another. For the dimensions of iron rods, see the instructions adopted by the Academy of Science, Paris, May 20, 1875; Lightning Rod Conference, pp. 67-8. [31] See letter of Mr. R. S. Newall, F. R. S., in the _Times_, May 30, 1879. [32] See Nature, June 12, 1879, vol. xx., p. 146. [33] See letter of Mr. Tomes in Nature, vol. xx., p. 145; also Lightning Rod Conference, pp. 210-15. [34] See Anderson, Lightning Conductors, pp. 208-10. [35] See Lightning Rod Conference, pp. 208-10; see also the note at the end of this Lecture, p. 52. [36] Lecture on Thunderstorms, Nature, vol. xxii., pp. 365, 437. See, also, a very interesting paper by the late Professor J. Clerk Maxwell, read before the British Association at Glasgow in 1876, and reprinted in the report of the Lightning Rod Conference, pp. 109, 110. [37] Nature, vol. xxxi., p. 459. [38] See further information on this interesting subject in the Report of the Lightning Rod Conference, pp. 233-5. [39] See “Die Theorie, die Anlage, und die Prüfung der Blitzableiter,” von Doctor W. Holtz, Griefswald, 1878. [40] See page 44. APPENDIX. RECENT CONTROVERSY ON LIGHTNING CONDUCTORS. The lecture on lightning conductors contained in this volume fairly represents, I think, the theory hitherto received on the subject. It is, moreover, entirely in accord with the report of the Lightning Rod Conference, brought out in 1883, by a committee of most eminent men, representing several branches of science, who were specially chosen to consider this question some ten years ago.