NAVIGATING THE AIR
My first impression of aerial navigation was, I confess, surprise to feel the air-ship going straight ahead. It was astonishing to feel the wind in my face. In spherical ballooning we go with the wind, and do not feel it. True, in rising and descending the spherical balloonist feels the friction of the atmosphere, and the vertical oscillation makes the flag flutter, but in the horizontal movement the ordinary balloon seems to stand still, while the earth flies past under it.
As my air-ship ploughed ahead the wind struck my face and fluttered my coat, as on the deck of a transatlantic liner, though in other respects it will be more accurate to liken aerial to river navigation with a steamboat. It is not like sail navigation, and all talk about "tacking " is meaningless. If there is any wind at all it is in a given direction, so that the analogy with a river current is complete. When there is no wind at all we may liken it to the navigation of a smooth lake or pond. It will be well to understand this matter.
Suppose that my motor and propeller push me through the air at the rate of 20 miles an hour, I am in the position of a steamboat captain whose propeller is driving him up or down the river at
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