. The period of the Encroaching of the Desert was at hand, and
the deeps were all astir with movement. But in the windless air was a
great peace. A calm of infinite stillness breathed everywhere. The flow
of Time, before it rushed away backwards, stopped somewhere between the
dust of stars and Desert. The mystery of sand touched every street with
its unutterable softness.

And Vance began without the smallest circumlocution. His voice was low,
in keeping with the scene, but the words dropped with a sharp
distinctness into the other's heart like grains of sand that pricked the
skin before they smothered him. Caution they smothered instantly;
resistance too.

"I have a message for you from my aunt," he said, as though he brought
an invitation to a picnic. Henriot sat in shadow, but his companion's
face was in a patch of light that followed them from the windows of the
central hall. There was a shining in the light blue eyes that betrayed
the excitement his quiet manner concealed. "We are going--the day after
to-morrow--to spend the night in the Desert; she wondered if, perhaps,
you would care to join us?"

"For your experiment?" asked Henriot bluntly.

Vance smiled with his lips, holding his eyes steady, though unable to
suppress the gleam that flashed in them and was gone so swiftly. There
was a hint of shrugging his shoulders.

"It is the Night of Power--in the old Egyptian Calendar, you know," he
answered with assumed lightness almost, "the final moment of
Leyel-el-Sud, the period of Black Nights when the Desert was held to
encroach with--with various possibilities of a supernatural order. She
wishes to revive a certain practice of the old Egyptians. There _may_ be
curious results. At any rate, the occasion is a picturesque one--better
than this cheap imitation of London life." And he indicated the lights,
the signs of people in the hall dressed for gaieties and dances, the
hotel orchestra that played after dinner.

Henriot at the moment answered nothing, so great was the rush of
conflicting emotions that came he knew not whence. Vance went calmly on.
He spoke with a simple frankness that was meant to be disarming. Henriot
never took his eyes off him. The two men stared steadily at one another.

"She wants to know if you will come and help too--in a certain way
only: not in the experiment itself precisely, but by watching merely
and--" He hesitated an instant, half lowering his eyes.

"Drawing the picture," He