Two years ago I was travelling by diligence in the Sahara Desert on the great caravan route, which starts from Beni-Mora and ends, they say, at Tombouctou. For fourteen hours each day we were on the road, and each evening about nine o'clock we stopped at a Bordj, or Travellers' House, ate a hasty meal, threw ourselves down on our gaudy Arab rugs, and slept heavily till the hour before dawn, drugged by fatigue, and by the strong air of the desert. In the late afternoon of the third day of our journeying we drove into a sandstorm.