Often on that march Challis's blood boiled as he saw how his men were treated, and knew his helplessness to defend them. The Tubus urged them with whips, sometimes with the points of their swords. The wretched Hausas, some of whom were weak with sickness, panted along under their loads, striving to keep pace with the impatient horsemen. They dared not even groan, for a murmur brought the lash on their shoulders. When Challis protested through Kulana, explaining that the men were ill, Goruba only grinned and mocked him. By-and-by, however, it became apparent to Goruba that the men were incapable of further marching. The slave-driver is usually callous enough as to the fate of his victims; he will watch them with unconcern growing weaker and weaker, see them drop in their tracks, sometimes kill them in sheer rage at their inability to keep up. But Goruba did not wish to lose these men. They were themselves valuable. They bore valuable loads. It would be a mistake to over-drive them. In the afternoon, therefore, some hours earlier than a march is usually ended, he gave the order to halt. The Hausas laid down their burdens, and threw themselves on the ground in utter exhaustion. [Illustration: THE PRISONER] Challis himself was in little better case. He had not been given a load to carry, but he had felt himself growing weaker and weaker as the day wore on. Though his wound was not serious, he had lost some blood, and was enfeebled by the shock and the bruises he had suffered in the trampling. When he lagged on the march, the man to whose saddle he was fastened prodded him in the back with the point of his spear. His own sufferings, and the sufferings of his men, made him realise with new force the horrors of slave-driving, which, in spite of all efforts to crush it, still exists in parts of the dark continent. It was therefore with inexpressible relief that he welcomed the order to halt. The place chosen for camp was the crest of a slight undulation. The soil was sandy, and hot from the beating of the sun upon it all day. There were a few scrubby bushes dotted around, but no grass. Nor was there a stream in which the marchers could bathe their burning feet. The Tubus fetched water from a small water-hole near by. They made a meal of the provisions carried in their wallets. The Hausas consumed the last of their food. Challis was forced to ask permission to open one of the tins of preserved meat which formed part of the men's loads. The Tubus gathered round him, and watched with childish curiosity as he cut the tin open. They were mute with astonishment when they saw what it contained. They hardly allowed Challis time to take from it sufficient for his supper, before they began to quarrel about the ownership of the tin. Goruba, hearing the noise, came and settled the matter by swallowing the rest of the meat in two or three great gulps, and taking the tin as a present for one of his wives.