May it not also be the fact that the fuses melted during thunderstorms in their neighbourhood are melted by reason of the effect of the electric radiations or surgings of the lightning stroke throwing a rush of the current already in the circuit through the fuse rather than by the addition of any new current to the circuit by the atmospheric electricity itself. In this connection Lodge writes: “There are some who think that lightning flashes can do none of these secondary things. They are mistaken.” In this as in other directions the new facts have a practical bearing and a pursuit of further experiments may lead, as often happens, to unexpected developments. So far as carbon contacts are concerned and the fact that Hertzian waves, like mechanical motion, reduce their resistance, a curious problem is suggested as concerns the principle upon which some carbon transmitters act. An exclusive monopoly of all carbon transmitters is based upon the claim that the variations in resistance are produced by variations in _pressure_ due to a mechanical force, viz., sound waves. If my experiments, above detailed, are exact, two facts appear: 1. That another form of motion, ether vibration, causes a variation of resistance of carbon contacts. 2. That it remains to be proved that variation of _pressure_ is the only means of varying the current strength, for variation of molecular contact occurs in the present instance without any evidence that it is due to variation of pressure. APPENDIX IV. ON THE DISELECTRIFICATION OF METALS AND OTHER BODIES BY LIGHT. Referring to a footnote to my Royal Institution lecture, on page 11, Messrs. Elster and Geitel have been good enough to call my attention to a great deal of work done by them in the same direction. To make amends for my ignorance of this work at the time of my Royal Institution lecture, and to make it better known in this country, I make abstract of their Papers as follows:-- _Wiedemann’s Annalen, 38, p. 40.--“On the Dissipation of Negative Electricity by Sun- and Daylight.”_ With a view to Arrhenius’ theory concerning atmospheric electricity, we arranged experiments on the photo-electric power of sunlight and diffuse daylight at Wolfenbüttel from the middle of May to the middle of June, 1889. Hoor alone had observed the effect of sunlight; other experimenters had failed to find it, but we find a discharging effect even in diffuse daylight.