s, and now the time had come to justify that trust and prove his
own devotion. It should be proved to the letter, and if there was
cause for vengeance, the proof should be written in blood and flame
over all the wide dominions of the Tsar. Grief might come after, when
there was time for it; but this was the hour of action, and a strange
savage joy seemed to come with the knowledge that the safety of the
woman he loved now depended mainly upon his own skill and daring.

Colston respected his silence, and waited until he spoke. When he did
he was astonished at the difference that those few minutes had made
in the young engineer. The dreamer and the enthusiast had become the
man of action, prompt, stern, and decided. Colston had never before
heard from his lips the voice in which he at length said to him--

"Where is this place? How far is it as the crow flies from here?"

"At a rough guess I should say about two thousand two hundred miles,
almost due east, and rather less than two hundred miles on the other
side of the Ourals."

"Good! That will be twenty hours' flight for us, or less if this
south-west wind holds good."

"What!" exclaimed Colston. "Twenty hours, did you say? You must
surely be making some mistake. Don't you mean forty hours? Think of
the enormous distance. Why, even then we should have to travel over
sixty miles an hour through the air."

"My dear fellow, I don't make mistakes where figures are concerned.
The paradox of aerial navigation is 'the greater the speed the less
the resistance.'

"In virtue of that paradox I am able to tell you that the speed of
the _Ariel_ in moderate weather is a hundred and twenty miles an
hour, and a hundred and twenty into two thousand two hundred goes
eighteen times and one-third. This is Wednesday, and we have to be on
the Asiatic frontier at daybreak on Friday. We shall start at dusk
to-night, and you shall see to-morrow's sun set over the Ourals."

"That means from the eastern side of the range!"

"Of course. There will be no harm in being a few hours too soon. In
case we may have a long cruise, I must have additional stores, and
power-cylinders put on board. Come, you have not seen the _Ariel_
yet.

"I have made several improvements on the model, as I expected to do
when I came to the actual building of the ship, and, what is more
important than that, I have immensely increased the motive power and
economised space and weight at the same time. In fact, I d