Neither Sime nor Ali Mohammed were of highly strung temperament, neither subject to those subtle impressions which more delicate organisations receive, as the nostrils receive an exhalation, from such a place as this. But Dr. Cairn and his son, though each in a different way, came now within the _aura_ of this temple of the dead ages. The great silence of the desert--a silence like no other in the world; the loneliness, which must be experienced to be appreciated, of that dry and tideless ocean; the traditions which had grown up like fungi about this venerable building; lastly, the knowledge that it was associated in some way with the sorcery, the unholy activity, of Antony Ferrara, combined to chill them with a supernatural dread which called for all their courage to combat. "What now?" said Sime, descending from his mount. "We must lead the donkeys up the slope," replied Dr. Cairn, "where those blocks of granite are, and tether them there." In silence, then, the party commenced the tedious ascent of the mound by the narrow path to the top, until at some hundred and twenty feet above the surrounding plain they found themselves actually under the wall of the mighty building. The donkeys were made fast. "Sime and I," said Dr. Cairn quietly, "will enter the pyramid." "But--" interrupted his son. "Apart from the fatigue of the operation," continued the doctor, "the temperature in the lower part of the pyramid is so tremendous, and the air so bad, that in your present state of health it would be absurd for you to attempt it. Apart from which there is a possibly more important task to be undertaken here, outside." He turned his eyes upon Sime, who was listening intently, then continued: "Whilst we are penetrating to the interior by means of the sloping passage on the north side, Ali Mohammed and yourself must mount guard on the south side." "What for?" said Sime rapidly. "For the reason," replied Dr. Cairn, "that there is an entrance on to the first stage--" "But the first stage is nearly seventy feet above us. Even assuming that there were an entrance there--which I doubt--escape by that means would be impossible. No one could climb down the face of the pyramid from above; no one has ever succeeded in climbing up. For the purpose of surveying the pyramid a scaffold had to be erected. Its sides are quite unscaleable." "That may be," agreed Dr. Cairn; "but, nevertheless, I have my reasons for placing a guard over the south side. If anything appears upon the stage above, Rob--_anything_--shoot, and shoot straight!" He repeated the same instructions to Ali Mohammed, to the evident surprise of the latter.