Camels brought up on the sandy plains of the Arabian coast had delicate pads to their feet; and if such animals were taken suddenly inland for long marches over flints or other heat-retaining ground, their soles would burn, and at last crack in a blister; leaving quick flesh, two inches or more across, in the centre of the pad. In this state they could march as ever over sand; but if, by chance, the foot came down on a pebble, they would stumble, or flinch as though they had stepped on fire, and in a long march might break down altogether unless they were very brave. So we rode carefully, picking the softest way, Auda and myself in front.