"No, that is quite right," he replied. "That is half the surface pressure, which shows that we are two and a half miles high. I have four batteries in, and we are going at a constantly increasing speed now." I could easily believe it, for the wind howled around my compartment and whistled over the rudder aperture in a most dismal way. Whenever the rudder was changed, there was a new sound to the moaning. Still, as I looked back at the clouds, I saw that no wind was moving them. It was not wind, but only the air whistling as we rushed through it. "Watch the barometer, and let me know the exact time when it registers seven and a half inches," said the doctor. "We shall be five miles high then, and we started at nine o'clock to a second." I noted the rapidly sinking mercury and opened my watch. When it was just at seven and a half, I looked at the watch, and it said half a minute after nine. Knowing that could not be correct, I held it to my ear and discovered it was stopped. I attempted to wind it, but found it almost wound up. "Something wrong with my watch, Doctor. You will have to look." "Half a minute after nine, that can't be right!" he exclaimed. Then as the truth flashed upon him he added,-- "There is the first thing I have overlooked! Our watch springs are steel, and the magnetic currents affect them. It is strange I did not think of that, for I knew a mariner's compass would be of no use to us in steering on account of the currents. For that reason I have risen above the clouds so as to steer by the stars. I am making for the North Star yonder, now." "We will have to get back to the same primitive methods of measuring time," I put in. "Neither weight clocks nor spring clocks would have been of any account. And an hour glass would tell a different tale just as gravity varied. We will have to rely on the Moon and stars, and it may be rather awkward." But I did not then appreciate how awkward it would be when even the markings of day and night would be taken away from us. "We can count our pulse or go by our stomachs," said the doctor, who was really disappointed at having forgotten anything. But he was destined to get used to that. Presently he inquired,-- "What is the barometer now? Perhaps we are high enough for the present." "There is scarcely two inches of mercury in the tube!" I cried out. He hesitated for a moment as if calculating, and then said,-- "That makes us ten miles high. Work the rudder gradually very much farther out for this thinner atmosphere, and we will try falling awhile, with a long slant to northward."