eleven o'clock
At length , however , when their watches marked the hour of seven a.m. they became aware of a dim , ghostly light filtering down upon them from above and stealthily revealing the presence of tree-trunk , twisted creepers , and tangled underscrub at gradually widening distances from them . Whereupon they charged and lighted their pipes afresh , extinguished their torches , and , after allowing themselves a few minutes longer to enable their eyes to become accustomed to the dim , sombre twilight that alone pervaded those illimitable forest aisles , set out upon a course which they agreed would ultimately lead them back to the river . Their course was anything but a straight one , for they were obliged to wind hither and thither between and around enormous masses of tangled , impenetrable undergrowth ; and there were many occasions when they were compelled to go some little distance in a direction the very opposite of that which they wished to follow , ere they could again hit off a practicable path leading northward . Yet notwithstanding this , they began to feel some disappointment and recurrence of anxiety when , at eleven o'clock in the forenoon , they still seemed as far off as ever from finding the river . There was nothing for it , however , but to press forward as they were going ; and this they did , in somewhat noisy fashion -- for there seemed to them to be no very especial reason for silence -- until there suddenly broke upon their ears a deep , hollow , drumming sound , speedily followed by a series of loud , fierce roars . The sounds emanated from somewhere close at hand , and after a moment 's instinctive pause to listen , they all with one accord hastened forward to investigate , with the result that they suddenly found themselves emerging from the cramped and gloomy environment of the forest depths into a comparatively open arena , roughly circular in shape , and nearly a mile in diameter , thickly carpeted with rich , lush grass , and but sparsely dotted with trees . As the wanderers entered this space , they saw , about a dozen yards away , a very fine gorilla , upreared , with his back toward them , fiercely beating his chest with his huge fists , and giving vent to a succession of savage , barking roars .