unded cloud contours could easily be likened to the domes of
snow-covered mountains. It was really difficult to conceive that that
amorphous expanse was not actually solid. Here and there flocculent
towers and summits heaved up, piled like mighty snow dumps, toppling
and crushing into one another, as the breezes stirred them.

Then there were tiny wisps of cloud, more delicate and frail than
feathers or the down of a dandelion-blow. Chasms hundreds of feet
deep, sheer columns, and banks, extended almost beyond eye-reach.
Between the flyers and the sun stretched isolated towers of cumulus,
cast up as if erupted by the chaos below. The sunlight, filtering
through this or that gossamer bulk, was scattered into every
conceivable shade and monotone. And around the margins of the heaving
billows the sun's rays played unhampered, unrestricted, outlining all
with edgings of the purest silver.

The scene was one of such extravagance that the brain was staggered
with what the eye tried to register. Below the aviators, the shadow of
their machine pursued them on white film like a grotesque gray bird of
some supernatural region. The shadow followed tirelessly, gaining as
the hour of noon approached, gaining still as afternoon began to
gather, swell, and wane; and always it skipped from crest to crest down
there just below, jumping gulfs like a bewitched phantom.

It was so cold at this height that the aviators had to put on their
heaviest garments, and they were content to open the windows only a
slight way for ventilation.

When darkness fell, they were still flying high, though at reduced
speed, as John was afraid that a rate too much over schedule might
cause them to overrun their destination before daylight could disclose
its outlines to them. Every half-hour the pilot's helper checked up
their position on the chart. Had this not been done from the very
start of the trip, they never could have struck their ports with the
accuracy they did, and disaster would have been the result, if not
death to the crew.

As it was, they had taken every precaution they could. When they had
crossed the Atlantic they had been careful to inflate the four spare
inner tubes of their landing wheels, as these would make capital
life-preservers in case the flyers were thrown into the sea; and one of
the last things they did before leaving Aden was to see that the tubes
were still inflated.

The long night passed with considerable anxi