“Thereby hangs a tale,” he said. “I have not been able to learn anything about the way of making these batteries. Indeed, I did not try; there was no time to spare from the more urgent matters. What I have learned is that they have two kinds of battery, one much more easily made and which wastes very much more quickly, but which drives the cars faster while it lasts. That is the sort that we are using now. The other sort is more difficult of production and wastes very much more slowly, and drives the cars more slowly. On long voyages, as I understand, they use the latter sort mainly, reserving the former sort for short voyages and for spurts. Now the spare battery is of the sort that wastes more slowly and drives the car more slowly; whereas it is a battery of the other sort that has been put into operation, what does that mean? I don’t know how Leäfar got the batteries, and I don’t know what he knows about their use. I think it would not be safe to assume that he is beyond the risk of making mistakes. They have to learn things just as we have.” “He got the battery for us,” I replied, “and it seems the safer thing to conclude that he knows more about it than we do. But what does it matter any way?” “I’ll tell you as near as I can. Don’t mind a bit of rigmarole or what seems to be such. Trust me for coming to the point all the time.” “Go ahead,” said I. “Very well,” he said, “I want to know, or to make as near a guess as possible, at two or three things. “(1.) How fast are we going now, and how far are we from the wire? or how far were we when we started? That means, how soon shall we reach the wire? “(2.) What are we to do if we overshoot the wire? We have no way of telling the longitude; my watch indeed is a capital chronometer, but I have altered it by the sun two or three times as near as I could. Besides, we cannot get the sun’s place near enough. Now, if we overshoot the wire, we shall either have to cross the continent or else to make southward and look out for the Darling or for the Murray; or, failing either, for the sea. “I do not think that we can have made much more than three hundred miles of westing from the Daly Waters, and suppose that we are now travelling at the rate of thirty miles an hour, which is not unlikely, we ought, if we keep up the rate, to make the wire at seven or eight o’clock in the morning. If I have overrated the distance or underrated our speed only a little, we may cross the wire before sunrise. “So far, then, it seems clear to me that we ought to be travelling at the slow rate instead of the quick rate. I thought of this before, but I saw no means of securing one of the larger batteries, and I knew that I could slow the speed of the smaller one.