A box of new books kept us busy all afternoon, and then, before sundown, the Maluka suggested a farewell stroll among the pools.

The Bitter Springs—­a chain of clear, crystal pools, a long winding chain, doubling back on itself in loops and curves—­form the source of the permanent flow of the Roper; pools only a few feet deep, irregular and wide-spreading, with mossy-green, deeply undermined, overhanging banks, and lime-stone bottoms washed into terraces that gleam azure-blue through the transparent water.

There is little rank grass along their borders, no sign of water-lilies, and few weeds within them; clumps of palms dotted here and there among the light timber, and everywhere sunflecked, warm, dry shade.  Nowhere is there a hint of that sinister suggestion of the Reach.  Clear, beautiful, limpid, wide-spreading, irregular pools, set in an undulating field of emerald-green mossy surf, shaded with graceful foliage and gleaming in the sunlight with exquisite opal tints—­a giant necklace of opals, set in links of emerald green, and thrown down at hazard to fall in loops and curves within a forest grove.

It is in appearance only the pools are isolated; for although many feet apart in some instances, they are linked together throughout by a shallow underground river, that runs over a rocky bed; while the turf, that looks so solid in many places, is barely a two-foot crust arched over five or six feet of space and water—­a deathtrap for heavy cattle; but a place of interest to white folk.

The Maluka and I wandered aimlessly in and out among the pools for a while, and, then coming out unexpectedly from a piece of bush, found ourselves face to face with a sight that froze all movement out of us for a moment—­the living, moving head of a horse, standing upright from the turf on a few inches of neck:  a grey, uncanny, bodyless head, nickering piteously at us as it stood on the turf at our feet.  I have never seen a ghost, but I know exactly how I will feel if ever I do.

For a moment we stood spellbound with horror, and the next, realising what had happened, were kneeling down beside the piteous head.  The thin crust of earth had given way beneath the animal’s hindquarters as it grazed over the turf, and before it could recover itself it had slipped bodily through the hole thus formed, and was standing on the rocky bed of the underground river, with its head only in the upper air.

The poor brute was perishing for want of food and water.  All around the hole, as far as the head could reach, the turf was eaten, bare, and although it was standing in a couple of feet of water it could not get at it.  While the Maluka went for help I brought handfuls of grass, and his hat full of water, again and again, and was haunted for days with the remembrance of those pleading eyes and piteous, nickering lips.