nough now the dull sound of trampling hoofs, the jingling of trappings,
and every now and then an angry snort or squeal as some ill-tempered
beast resented the too near approach of one of its own kind.

Then all at once, as the sounds came nearer, there was heard plainly
enough the muttering, whining cry of a camel, followed by more and more
proofs then that the coming party was one of greater strength than it
had seemed to be at first.

Just then the Sheikh came back out of the darkness, to halt his camel
close up by the professor's.

"It is not English cavalry, Excellencies," he said, "but a native force.
I think it must be the Baggara chief and his men returned."

At that moment a peculiar cry rang out from a couple of hundred yards or
so away--a weird, strange whoop that might have come from some night
bird sweeping through the darkness overhead.

But it was human, and answered directly by the Baggara train close at
hand, and directly after there was a loud shout, and a crowd of horsemen
galloped up out of the mysterious-looking gloom, to mingle with the
party about to start on their desert ride.

CHAPTER TWENTY TWO.

NEARING THE GOAL.

It was more from hearing than seeing that Frank Frere gathered the fact
that the Baggara chief had returned, for after a short pause the camel
train was once more in motion, and they were ordered to keep steadily in
line in the advance to the desert in the opposite direction to that by
which the newcomers had arrived.

At first the two parties formed the train alone, for the fresh arrivals
had halted to water their horses and camels, quite an hour passing
before the sound of approaching horsemen announced that the whole force
was in motion, overtaking them at a sharp canter, but only to subside
directly into the regular, slow camel pace, which was kept on hour after
hour till the dawn, when, looking back, Frank made out that the train
extended for nearly half a mile to the rear, being made up of a long
line of camels, followed by a troop of many horsemen.

It was nearly all surmise, but judging from the number of camels, which
were certainly double those that the Baggara had before during their
stay by the fountains, they had been engaged in some successful foray,
for as the light grew stronger the baggage animals seemed to be very
heavily laden.

This idea naturally suggested that the wild horsemen had been engaged in
some desperate encounter, and half laughingly th