Page:Sim pall-mall-magazine 1904-01 32 129.pdf/17



Photo by Gallard.

OW does it feel to travel in an air-ship? My first impression of aerial navigation was surprise to feel the air-ship going straight ahead. It was astonishing to feel the wind in my face. In spherical balloons 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 vertical oscillation often makes the flag flutter; but in all its horizontal movements the ordinary balloon seems to stand still while the earth flies past under it.

This was on the first of all my trips, on Sept. 20th, 1898, the air-ship making only moderate speed. Nevertheless, as it 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 at all like sail-navigation ; and all talk about "tacking" is meaningless. If there is any wind at all, it must, regularly, be in a given direction, so that the analogy with a river-current becomes complete. When there is no wind, 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 twenty miles an hour. I am in the position of a steamboat captain whose propeller is driving him up or down the river at the rate of twenty miles an hour. Imagine the current to be ten miles an hour. If he navigates against the current, he accomplishes ten miles an hour with respect to the shore, though he has been travelling twenty miles an hour through the water. If he goes with the current, he accomplishes thirty miles an hour with respect to the shore, though he has not been going any faster through the water. This is one of the reasons why it is so difficult to estimate the speed of an air-ship.