The new views put forward by Professor Lodge were based, in great measure, on his theory that a lightning discharge consisted of a series of rapid oscillations. But this theory should be received with great caution. It seemed to be nothing more than a deduction from certain mathematical formulas, and was not supported by any solid basis of observation or experiment. Besides, there were many facts against it. They all knew that a flash of lightning magnetized steel bars, deranged the compasses of ships at sea, and transmitted signals on telegraph wires. But such effects could not be produced by a series of oscillations, which, being equal and opposite, would neutralize each other. It was alleged that these rapid oscillations occurred in the discharge of a Leyden jar. That might be true, and probably was true; but they were not dealing with Leyden jars, they were dealing with flashes of lightning. If there was any analogy between the discharge of a Leyden jar and a flash of lightning, it was to be found, not in the external discharge employed by Professor Lodge in his experiments, but in the bursting of the glass cylinder between the two coatings of the jar. Lord Rayleigh thought the experiments of Professor Lodge were likely to have important practical applications to lightning conductors. But though these experiments were valuable as suggestions, they did not furnish a sufficient ground for adopting any new system of protection. It was only by experience with lightning conductors themselves that the question could be finally settled. Sir William Thomson hoped for great fruit from the further investigation of self-induction in the case of sudden electrical discharges. He warmly encouraged Professor Lodge to continue his researches; but he expressed no decided opinion on the question at issue. Incidentally he observed that the best security for a gun-powder magazine was an iron house; no lightning conductor at all, but an iron roof, iron walls, and an iron floor. Wooden boards should, of course, be placed over the floor to prevent the danger of sparks from people walking on sheet-iron. This iron magazine might be placed on a dry granite rock, or on wet ground; it might even be placed on a foundation under water; it might be placed anywhere they pleased; no matter what the surroundings were, the interior would be safe. He thought that was an important practical conclusion which might safely be drawn from the consideration of these electrical oscillations and the experiments regarding them.