For variety we determined to work by Maan. So we rode up to Batra, climbing out of heat into cold, out of Arabia into Syria, from tamarisk to wormwood. As we topped the pass and saw the bloodred stain on the hills above the leech-infested wells, there met us a first breath of the northern desert; that air too fine to describe, which told of perfect loneliness, dried grass, and the sun on burning flints.

The guides said that Kilometre 475 would be good for mining: but we found it beset by blockhouses, and had to creep shyly away. We marched down the line till it crossed a valley on a high bank, pierced by bridges on each side and in the middle. There, after midnight, we laid an automatic mine of a new and very powerful lyddite type. The burying took hours, and dawn caught us as we worked. There was no perceptible lightening, and when we stared round to know where the dark was yielding, we could see no special onset of the day. Long minutes afterwards the sun disclosed itself, high above the earth’s rim, over a vignetted bank of edgeless mist.