It was useless, but I had known that from the beginning. What would be more interesting would be to question her, and that I had wished to do for some time, but she always put me off with a pretty gesture and a shake of her head, insisting that I answer some of her questions instead, but this time I insisted.
“Tell me, please,” I asked, “how you came to the spot where you were captured, how you flew, and what became of your wings, and why, when they tore them from you, it did not injure you?”
“The wings do not grow upon us,” she explained, “we make them and fasten them upon our arms.”
“Then you can support yourself in the air with wings fastened to your arms?” I demanded, incredulously.
“Oh, no,” she said, “the wings we use simply for propelling ourselves through the air. In a bag, upon our backs, we carry a gas that is lighter than air. It is this gas which supports us, and we carry it in such quantities as to maintain a perfect equilibrium, so that we may float at any altitude, or with our wings rise or fall gently; but as I hovered over Laythe, came the air that runs, and seizing me with its strong arms bore me off across the surface of Va-nah. Futilely I fought against it until I was spent and weak, and then it dropped me into the clutches of the Va-gas, for the gas in my bag had become depleted. It was not intended to carry me aloft for any great length of time.”
She had used a word which, when I questioned her, she explained so that I understood that it meant time, and I asked her what she meant by it and how she could measure it, since I had seen no indication of the Va-gas having any conception of a measurable aspect of duration.
Nah-ee-lah explained to me that the Va-gas, who were a lower order, had no means of measuring time, but that the U-ga, the race to which she belonged, had always been able to compute time through their observation of the fact that during certain periods the bottoms of the hoos, or craters, were illuminated, and for another period they were dark, and so they took as a unit of measure the total period from the beginning of this light in a certain crater to its beginning again, and this they called a _ula_, which corresponds with a sidereal month. By mechanical means they divide this into a hundred parts, called _ola_, the duration of each of which is about six hours and thirty-two minutes earth time. Ten ulas make a _keld_, which one might call the lunar year of about two hundred and seventy-two days earth time.