Page:My Airships.djvu/258

 like my "No. 6" seems always to commence at 25 to 30 kilometres (15 to 18 miles) per hour through the air. Now, probably, when one passes this speed considerably—say at the rate of 50 kilometres (30 miles) per hour—all tangage or pitching will be found to cease again, as I myself experienced when flying homeward on the wind in the voyage last described.

Speed must always be the final test between rival air-ships, because, in itself, speed sums up all other air-ship qualities, including "stability." At Monaco, however, I had no rivals to compete with. Furthermore, my prime study and amusement there was the beautiful working of the maritime guide rope; and this guide rope, dragging through the water, must of necessity retard whatever speed I made. There could be no help for it. Such was the price I must pay for automatic equilibrium and vertical stability—in a word, easy navigation—so long as I remained the sole and solitary navigator of the air-ship.

Nor is it an easy task to calculate an air-ship's speed. On those flights up and down the Mediterranean coast the speed of my return to Monaco, wonderfully aided by the wind, could bear no relation to the speed out, retarded by the wind,