its own fair share
of work at the oars.

Once fairly away from the ship's side we were immediately swallowed up
by the impenetrable mist; and for a considerable time the flotilla
glided gently along, without a sight or sound to tell us whether we were
going right or wrong; without the utterance of a word on board either of
the boats; and with only the slight muffled sound of the oars in the
rowlocks and the gurgle of the water along the boats' sides to tell that
we were moving at all. The silence would have been oppressive but for
the slight murmuring swirl and ripple of the great river and the
chirping of the countless millions of insects which swarmed in the bush
on both banks of the stream. The latter sent forth so remarkable a
volume of sound that when first told it was created by insects alone I
found my credulity taxed to its utmost limit; and it was not until I was
solemnly assured by Mr Austin that such was the case that I quite
believed it. It was not unlike the "whirr" of machinery, save that it
rose and fell in distinct cadences, and occasionally--as if by
preconcerted arrangement on the part of every individual insect in the
district--stopped altogether for a few moments. Then, indeed, the
silence became weird, oppressive, uncanny; making one involuntarily
shuffle nearer to one's neighbour and glance half-fearfully over one's
shoulder. Then, after a slight interval, a faint, far-off signal
_chirp! chirp_! would be heard, and in an instant the whole insect-world
would burst into full chorus once more, and the air would fairly vibrate
with sound. But the night had other voices than this. Mingled with the
_chirr_ of the insects there would occasionally float off to us the
snarling roar of some forest savage, the barking call of the deer, the
yelping of a jackal, the blood-curdling cry of a hyena, the grunt of a
hippopotamus, the weird cry of some night-bird; and--nearer at hand,
sometimes apparently within a yard or so of the boats--sundry mysterious
puffings and blowings, and sudden faint splashings of the water, which
latter made me for one, and probably many of the others who heard them,
feel particularly uncomfortable, especially if they happened to occur in
one of the brief intervals of silence on shore. Once, in particular,
during one of those silent intervals, my hair fairly bristled as the
boat was suddenly but silently brought up all standing by coming into
violent collision with some object wh