n feet high and covering half
the distance between them. It alighted easily upon the two long,
jointed metal limbs upon which it had leapt, and continued to keep the
lens-tubes turned toward Dan, so he knew that the grotesque metal
thing was _watching him_.

The limbs, he observed, were similar to the hind legs of a
grasshopper, both in shape and position. And evidently the thing leapt
upon them in about the same way. Then he noticed another curious thing
about it.

Three little bars of metal projected above the thickest part of its
case, on the upper side. Their ends were joined by a little ring,
three inches across. The tiny metal ring glowed with purple
luminosity. A purple haze seemed to cling about it, as to the huge
ring Dan had seen on the towers above the peak. And suspended inside
this ring was a tiny metal needle, shimmering with pulsating white
fire.

On the back of this metal monster was a miniature replica of the
strange mechanism upon the pinnacle. The little needle pointed up the
canyon. A glance that way showed Dan that it pointed at the great
device upon the mountain, which looked even more brilliant on this
gloomy morning than in the uncertain radiance of the moon. The
colossal ring was shrouded in a splendid mantle of purple flame; and
the long, slender needle, which seemed to have swung on down to follow
Mars below the horizon, still throbbed with scintillating white fire.

For several minutes the two stood there, studying each other. A naked
man, tense and bewildered in the presence of mysterious forces--and a
grotesque machine, cased in gleaming white metal, whose parts seemed
to duplicate most of the functions of a living creature.

Then one of the writhing tentacles that shot from the "head" of the
machine reached back under the metal case, and reappeared grasping
what appeared to be a flat disk of emerald, two inches across and half
an inch thick.

This green disk it held up, with a flat side toward Dan. There was no
sound, but a flash of green light came from it, cutting a wide swath
into the jungle, and littering its path with smoking and flaming
debris.

* * * * *

But Dan, expecting something of the kind, had flung himself sidewise
into the shelter of the boulder beside which he had slept. Behind it,
he gathered his feet under him, picked up a rock of convenient size
for throwing, and waited, ready and alert.

He heard the soft humming sound on the