[Footnote 1:  So long as the Black Stone was at the Ka’aba, this building was the only spot in the world where the kiblah was circular, that is, where Moslems could pray all around it.  The Legion’s theft of the stone had completely dislocated all the most important beliefs and customs of Islam.]

“The most intense animosity of religious fanaticism will pursue us.  If the news of our exploit has, in any unaccountable way such as the Arabs know how to employ, reached Jannati Shahr, we are in for a battle royal.  If not, we still have a chance to use diplomacy.  A few hours now will determine the issue.

“We are approaching what will probably be the final goal of this expedition; a city beyond unknown mountains; a city that no white man has ever yet seen and that few have even heard of.  What the conditions will be there no one can tell; but—­”

“Not even Rrisa?” put in the major.  “Faith, now’s the time, if ever, to consult that lad!”

“Correct, for once,” assented the Master.  With purpose to deceive, he phoned for Rrisa.  No answer coming, he got Simonds on the wire and ordered him to find the orderly.  The investigation thus started would, he knew, soon bring out the fact of the orderly’s disappearance.  This line of action fairly started, he went on formulating his plans: 

“Major, look well to your guns.  For once you may have a chance to use them.  I have put my various pieces of apparatus in good condition, and have improvised some new features.  In addition, we have the second kappa-bomb.”

“But I trust we shall not be driven to a fight.  If diplomacy can win, there will be no bloodshed.  Otherwise, our only limit will be the total destruction of these unknown people, or our own annihilation.  It’s a case, now, of win what we are after, or end everything right there, beyond those mountains!”

He ascended to the upper port gallery, and concentrated himself on observation.  A certain change in the desert was becoming noticeable, as the air-liner flung herself at high speed into the south-east.  At times there must be a little rainfall here, or else some hidden source of water, for a scrub, of dwarf acacia, of camel-grass, and tamarisk had begun to show.

But as the black, naked mountains drew near, this gave place to flats white with salt, to jagged upcroppings of dull, yellowish rock—­how little they then suspected its true nature!—­and to detached cliffs sharp as a wolf’s teeth, with strata of greenish schist.

It was at 9:30 a.m. of May 28, that Nissr tilted her planes and soared abruptly over the first crags of the Iron Mountains.  At a height of forty-five hundred feet she sped above them, the heat of their sun-baked blackness radiating up against her wings and body.  No more terrible desolation could be imagined than this rock fortress, split with chasms and unsounded gorges, where here and there more of the yellow outcrops showed.  No life appeared, not even vultures.  For more than an hour, Nissr’s shadow leaped across this utter solitude of death.