[12] E. Branly, Comptes Rendus, Vol. CXI., p. 785; and Vol. CXII., p. 90.
[13] Journal Institution of Electrical Engineers, 1890, Vol. XIX., pp. 352-4; or “Lightning Conductors and Lightning Guards,” pp. 382-4.
[14] See Phil. Mag., Jan., 1894, p. 94, where this explanation (whether true or not) was first given, and where the author first published his fuller experience of coherer behaviour.
[15] This statement has been absurdly misunderstood, as if it was a prediction of what would always be the limit of sensitiveness for any apparatus and any sized sender. Nothing of the kind was in my mind. Such predictions are always preposterous, and I am not obliged to those who imagined that I had been guilty of one of them.—O. J. L., 1899.
[16] FitzGerald tells me that he has succeeded with carbon also. My experience is that the less oxidisable the metal, the more sensitive and also the more troublesome is the detector. Mr. Robinson has now made me a hydrogen vacuum tube of brass filings, which beats the coherer for sensitiveness. July, 1894.
[17] Cf. Trouton, in Nature, Vol. 39, p. 393; and many optical experiments by Mr. Trouton, Vol. 40, p. 398. Since then the above described and depicted apparatus for electro-optic experiments has been imitated in a neat, compact form by Prof. J. Chunder Bose, of Calcutta, and with it he has obtained many admirable and interesting optical results. See Proc. Roy. Soc.
[18] Proc. Roy. Soc., 1879 and 1882.
[19] “Dimensional Properties of Matter,” Phil. Trans., 1879.
[20] Evening Lecture on “Dust,” by the writer, see Nature, Vol. 31, p. 265; also Journal of the Royal Institution, May, 1886.
[21] Apparatus for the purpose is now in the catalogue of Messrs. Ducretet, of Paris, but they supply a pair of combs of points. It makes a more interesting experiment if only one point is used, in a moderate space, and the electric supply regulated so as not to hurry the disappearance of the smoke too quickly, but to exhibit the stages of aggregation which precede the final disappearance by deposition. Any kind of smoke serves, but a bit of magnesium ribbon burnt under a bell jar is cleanly and effective. It should be looked at in a window or other good light, of course.