Therefore I took my compass bearing afresh, and plunged into the scrub.  The sensation was of hitting solid ground after a long walk through sand.  We seemed fairly to shoot ahead and out of sight.  Whenever we came upon earth we marked it deeply with our heels; we broke twigs downwards, and laid hastily-snatched bunches of grass to help the trail we were leaving for the others to follow.  This, in spite of our compass, was a very devious track.  Besides, the thorn bushes were patches of spiky aloe coming into red flower, and the spears of sisal.

After an hour’s steady, swift walking the general trend of the country began to slope downwards.  This argued a watercourse between us and the hills around Kilimanjaro.  There could be no doubt that we would cut it; the only question was whether it, like so many desert watercourses, might not prove empty.  We pushed on the more rapidly.  Then we caught a glimpse through a chance opening, of the tops of trees below us.  After another hour we suddenly burst from the scrub to a strip of green grass beyond which were the great trees, the palms, and the festooned vines of a watercourse.  Two bush bucks plunged into the thicket as we approached, and fifteen or twenty mongooses sat up as straight and stiff as so many picket pins the better to see us.

For a moment my heart sank.  The low undergrowth beneath the trees apparently swept unbroken from where we stood to the low bank opposite.  It was exactly like the shallow, damp but waterless ravines at home, filled with black berry vines.  We pushed forward, however, and found ourselves looking down on a smooth, swift flowing stream.

It was not over six feet wide, grown close with vines and grasses, but so very deep and swift and quiet that an extraordinary volume of water passed, as through an artificial aqueduct.  Furthermore, unlike most African streams, it was crystal clear.  We plunged our faces and wrists in it, and took long, thankful draughts.  It was all most grateful after the scorching desert.  The fresh trees meeting in canopy overhead were full of monkeys and bright birds; festooned vines swung their great ropes here and there; long heavy grass carpeted underfoot.

After we had rested a few minutes we filled our empty canteens, and prepared to start back for our companions.  But while I stood there, Memba Sasa—­good, faithful Memba Sasa—­seized both canteens and darted away.

“Lie down!” he shouted back at me, “I will go back.”

Without protest—­which would have been futile anyway—­I sank down on the grass.  I was very tired.  A little breeze followed the watercourse; the grass was soft; I would have given anything for a nap.  But in wild Africa a nap is not healthy; so I drowsily watched the mongooses that had again come out of seclusion, and the monkeys, and the birds.  At the end of a long time, and close to sundown, I heard voices.  A moment later F., Memba Sasa, and about three-quarters of the men came in.  We