Atlas Nightshade

Day 139

“As soon as the balloon quits the earth, it is subjected to the

influence of many circumstances tending to create a difference in

its weight; augmenting or diminishing its ascending power. For

example, there may be a deposition of dew upon the silk, to the

extent, even, of several hundred pounds; ballast has then to be

thrown out, or the machine may descend. This ballast being

discarded, and a clear sunshine evaporating the dew, and at the

same time expanding the gas in the silk, the whole will again

rapidly ascend. To check this ascent, the only recourse is, (or

rather _was_, until Mr. Green’s invention of the guide-rope,) the

permission of the escape of gas from the valve; but, in the loss

of gas, is a proportionate general loss of ascending power; so

that, in a comparatively