"You know what a Leyden jar is? One of those things you charge with electricity, then you touch the tip, and bang, you get a shock. Well, this arrangement will make a super-Leyden jar of the _Monitor_. Every time she fires the gravity-beam, the positive charges will be put into her hull, and she'll soon be able to load up with a charge that will knock your eye out when it's let loose." "How's that? I know the outside of the _Monitor_ is covered with lead and so is the outside of a Leyden jar, but what's the connection?" "Well, it's this way. When you load up a Leyden jar the charge is not located in the plating, but in the glass. Now the _Monitor_ has a lot of steel, which will take up the charge just as well as glass. As soon as she fires the gravity-beam, these filaments will load her up with the left-over positives till she grunts. See?" "And since the earth is building up a lot of negative potential all the time, all you have to do is get your bird between you and the earth and then let go at him?" "That's the idea. It'll make an enormous spark-gap, and whatever is between us and the earth will get the spark. Sock them with a flash of artificial lightning. We'll use the light-beam as a conductor just as with the gravity-beam." "Sounds good, but I want to see the wheels go round. How much of a potential do you think you can build up in the _Monitor_?" "Well, let's see. We've got two thicknesses of nine-inch steel ... volts to a cubic inch ... by cubic inches.... Holy smoke, look how this figures out--over eleven million volts! That's theory, of course. There'll be some leakage in practice and we won't have time to build up that much negative potential every time we shoot, but if we only do half that well, we'll have a pretty thorough-going charge of lightning ... Peterson, come over here. I want you to make some changes on this barge." * * * * * _Monitor II_ stood on the ramp that had once held her elder sister, her outer coating of lead glimmering dully in the morning sun. Here and there, along her shining sides, were placed the windows through which her crew would watch the progress of the battle. Her prow was occupied by the same type of searchlight the earlier _Monitor_ had borne. But this time the searchlight was surrounded by a hedge of shining silver points--the discharge mechanism for the lightning flash. At the stern, instead of the opening running right through into the ship, was a tight bulkhead, with the connections for the gravity-beam rocket-mechanism leading through it. As Sherman had pointed out, "If this lightning is going to do us any good, we've got to get above our opponent, and those Lassans have built machines that made interplanetary voyages. We've got to make this boat air-tight so that we can go right after them as far as Rigel if necessary."