Burckhardt and his party were an hour and a half in crossing the valley. It was in the month of August that they made the tour, and they found the heat almost intolerable. There was not the slightest appearance of a road or of any other work of man at the place where they crossed it. Still they met with no difficulty in prosecuting their journey, for the sand, though deep, was firm, and the camels walked over it without sinking. In the various journeys which Burckhardt made in these solitary regions, he carefully noted all that he saw, and copious reports of his observations were afterward published by the society in whose service he was engaged. The only instrument which he had, however, for making observations, was a pocket compass, and this he was obliged to conceal in the most careful manner from his Arab attendants, for fear of betraying himself to them. If they had seen such an instrument in his possession, they would not only have suspected his true character, but would have believed the compass to be an instrument of magic, and would have been overwhelmed with superstitious horror at the sight of it. Accordingly, Burckhardt was compelled, not only to keep his compass in concealment, as he journeyed, but also to resort to a great variety of contrivances and devices to make observations with it without being seen. Sometimes, when riding on horseback, he would stop for a moment in the way, and watching an opportunity when the attention of his companions was turned in another direction, would hastily glance at his compass unseen, covering it, while he did so, beneath his wide Arabian cloak. When riding upon a camel he could not adopt this method, for a single camel in a caravan can not be induced to stop while the train is going on. To meet this emergency, the indefatigable traveler learned to dismount and mount again without arresting the progress of the animal. He would descend to the ground, and straying away for a moment into a copse of bushes, or behind some angle of a rock, would crouch down, take out his compass, ascertain the required bearing, make a note of it secretly in a little book which he carried for the purpose in the pocket of his vest, and then returning to the camel, would climb up to his seat and ride on as before. It was by such means as these that the existence and the leading geographical features of the valley of Arabah were first made known to the Christian world. ROBINSON'S VISIT TO EN-GEDI.