eveland assented, snapping about his body the heavy spring-straps of
his deeply cushioned seat, "but I'm just as anxious to get back to the
Hill as anybody can be to get me there. All set."

Rodebush waved his hand at the pilot and the purring whisper of the
exhausts changed instantly to a deafening, continuous explosion. The men
were pressed deeply into their shock-absorbing chairs as the _Silver
Sliver_ spun around her longitudinal axis and darted away from the
_Chicago_ with such a tremendous acceleration that the spherical warship
seemed to be standing still in space. In due time the calculated
midpoint was reached, the slim space-plane rolled over again, and, mad
acceleration now reversed, rushed on toward the Earth, but with
constantly diminishing speed. Finally a measurable atmospheric pressure
was encountered, the needle prow dipped downward, and the _Silver
Sliver_ shot forward upon her tiny wings and vanes, nose-rockets now
drumming in staccato thunder. Her metal grew hot; dull red, bright red,
yellow, blinding white; but it neither melted nor burned. The pilot's
calculations had been sound, and though the limiting point of safety of
temperature was reached and steadily held, it was not exceeded. As the
density of the air increased so decreased the velocity of the man-made
meteorite. So it was that a dazzling lance of fire sped high over
Seattle, lower over Spokane, and hurled itself eastward, a furiously
flaming arrow; slanting downward in a long, screaming dive toward the
heart of the Rockies. As the now rapidly cooling greyhound of the skies
passed over the western ranges of the Bitter Roots it became apparent
that her goal was a vast, flat-topped, conical mountain, shrouded in
violet light; a mountain whose height awed even its stupendous
neighbors.

While not artificial, the Hill had been altered markedly by the
engineers who had built into it the headquarters of the Triplanetary
Service. Its mile-wide top was a jointless expanse of gray armor steel;
the steep, smooth surface of the truncated cone was a continuation of
the same immensely thick sheet of metal. No known vehicle could climb
that smooth, hard, forbidding slope of steel; no known projectile could
mar that armor; no known craft could even approach the Hill without
detection. Could not approach it at all, in fact, for it was constantly
inclosed in a vast hemisphere of lambent violet flame through which
neither material substance nor destructive