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 the professor bantered his friends about their prospects.

“It means a revival of professional practice for you,” he said, “and that looks prosperous. You only lost your last patient a few hours ago—that is, if you have lost him—and now a score or two will come tumbling in.”

“Very well,” said the doctor coolly; “it shows that they approve of my treatment. I suppose we shall know at the first halt.”

This was many hours in coming, for a long, monotonous march was made right away to the south-west, with the pile of rocks they had left gradually sinking till quite out of sight, and then, with the sun growing hotter and hotter, there was nothing visible on any side but the long, level stretch of sand.

The halt was not made till near midday, when the heat had become unbearable, and horses and camels were growing sluggish, and showed plenty of indications of the need of whip and spur.

Then, apparently without orders, the little knot of horsemen, led by the Baggara who had had charge of the prisoners, drew up short and faced round, when taking them as the extreme limit the rest of the train formed themselves up into a well ordered group as they came on, till, with the Sheikh’s party and their guards as a kind of centre, and the camels with their loads behind, the horsemen closed them in as if for strategic reasons, and for the next half hour there was a busy scene, the camels being relieved of their loads as if the stay were to be of some hours’ length.

This was evidently intended, for fires were lit and food was prepared, many of the horsemen after picketing their horses settling down at once to coffee and pipes.

It was while Frank and his friends were partaking of an al fresco lunch, hastily prepared by Sam, that they had their first intimation of the Baggara chief being with the horsemen, for he cantered up to their temporary camp in company with his fierce-looking companion, leaped from his horse, and walked up to the Hakim at once, to give him a smile of recognition and hold out his left arm, which he tapped vigorously as if saying: “Look! Quite well again.” Then turning round to the Sheikh he signed to him to approach, and said a few words hastily, before nodding to the Hakim again, returning to his horse, mounting, and cantering away.

“Well, Ibrahim,” said the professor; “what does it mean?”