As soon as we got into the car Jack proceeded to raise it, as Niccolo Davelli had done, by inflating the balloons. This cannot be quickly done by any but a practised hand. If one who has had no practice tries it, the balloons are apt to get unequally inflated, and so the operator in bringing them every now and then to a state of equal inflation works the car from side to side with a rolling motion. Signor Davelli raised it quickly, without any rolling motion at all. This was only the second day of practice for Jack, but he managed by raising the car slowly to produce very little of the rolling motion. As soon as he had attained what he judged a sufficient height he connected the batteries with the paddles, and as the wind was, as the sailors say, “dead aft,” we soon began to make very great speed. I noticed now a point in the machinery which I had not observed before. There was a valve to each balloon, and both valves were worked by a sort of movable tap, one tap for both. The effect of these valves appeared to be the maintenance of the cars at a uniform height, or higher or lower as the driver wished. The tap was worked by the same machinery that drove the paddles. And if the driver for any reason wished to make the balloon act independently of the paddles he could disconnect the tap which worked the valves from the machinery which worked the paddles. The connection and disconnection was made by a handle within easy reach of the driver. After we had got well under way Jack began to speak. “Now, Bob,” he said, “do you think that you can steer while I speak? I have something to say. Here is the handle that you steer by: you see it is fixed so that you pull the way you want to go. That bright blue mark on the compass is East. Never mind the balloons, I will attend to them if there is need. You will have nothing to do but just keep the head of the car due east.” I found but little difficulty in managing the car as he directed, and after about twenty minutes’ practice I was able to steer and listen at the same time. Then Jack began, in a business-like manner, “You have seen the battery that we are driving by now; very well, here is the spare battery which, according to Leäfar’s promise, I find.” He pointed to the spare battery, which was placed on a sort of bracket within my sight. He took it off, or rather out of, the bracket with his two hands and put it back again. “I see,” said I, “that it is larger; it seems heavier than the other, and in some details different: what of that?”