ten o’clock
They did not float as I had expected ; but dropped down perpendicularly , like a bullet , en masse , and with the greatest velocity -- being out of sight in a very few seconds . I did not at first know what to make of this extraordinary phenomenon ; not being able to believe that my rate of ascent had , of a sudden , met with so prodigious an acceleration . But it soon occurred to me that the atmosphere was now far too rare to sustain even the feathers ; that they actually fell , as they appeared to do , with great rapidity ; and that I had been surprised by the united velocities of their descent and my own elevation . `` By ten o'clock I found that I had very little to occupy my immediate attention . Affairs went swimmingly , and I believed the balloon to be going upward with a speed increasing momently although I had no longer any means of ascertaining the progression of the increase . I suffered no pain or uneasiness of any kind , and enjoyed better spirits than I had at any period since my departure from Rotterdam , busying myself now in examining the state of my various apparatus , and now in regenerating the atmosphere within the chamber . This latter point I determined to attend to at regular intervals of forty minutes , more on account of the preservation of my health , than from so frequent a renovation being absolutely necessary .