But if we were bitten and stung by pismires and numberless tribes of insects by day, which every one will confess is as bad as being whipped with nettles, the night had also its alarms, terrors, and anxieties. In the dead of night, when the entire caravan was wrapped in slumber, a series of explosions would wake every one. Some tree or another was nightly struck by lightning, and there was a danger that half the camp might be mangled by the fall of one; the sound of the branches during a storm was like the roar of breakers, or the rolling of a surge on the shore. When the rain fell no voice could be heard in the camp, it was like a cataract with its din of falling waters. Each night almost a dead tree fell with startling crackle, and rending and rushing, ending with the sound which shook the earth.
There were trees parting with a decayed member, and the fall of it made the forest echo with its crash as though it were a fusillade of musketry. The night winds swayed the branches and hurled them against each other, amid a chorus of creaking stems, and swinging cables and rustle of leaves. Then there was the never-failing crick of the cricket, and the shriller but not less monotonous piping call of the cicadæ, and the perpetual chorus of frogs; there was the doleful cry of the lemur to his mate, a harsh, rasping cry which made night hideous, and loneliness and darkness repulsive. There was a chimpanzee at solitary exercise amusing himself with striking upon a tree like the little boys at home rattle a stick against the area railings. There were the midnight troops of elephants, who no doubt were only prevented from marching right over us by the scores of fires scattered about the camp.
Considering the number of sokos or chimpanzees in this great forest, it is rather a curious fact that not one of the Expedition saw one alive. My terrier “Randy” hunted them almost every day between Ipoto and Ibwiri, and one time was severely handled. I have heard their notes four several times, and have possessed a couple of their skulls, one of which I gave to the Pasha; the other, that I was obliged to leave at the time, was monstrously large.
In 1887 rain fell during eight days in July, ten days in August, fourteen days in September, fifteen days in October, seventeen days in November, and seven days in December, = seventy-one days. From the 1st of June, 1887, to the 31st of May, 1888, there were 138 days, or 569 hours of rain. We could not measure the rain in the forest in any other way than by time. We shall not be far wrong if we estimate this forest to be the rainiest zone on the earth.
For nine months of the year the winds blow from the South Atlantic along the course of the Congo, and up the Aruwimi. They bear the moisture of the sea, and the vapours exhaled by a course of 1400 miles of a river which spreads from half-a-mile to sixteen miles wide, and meeting on their easterly course the cold atmosphere prevailing at the high altitude they descend upon the forest almost every alternate day in copious showers of rain. This forest is also favourably situated to receive the vapours exhaled by Lakes Tanganika, the Albert Edward, and Albert Lakes. While standing in the plain on the verge of the forest, I have seen the two rain clouds, one from the westward and one from the eastward, collide and dissolve in a deluge of rain on Pisgah Mount and the surrounding country. Besides the rains, which lasted ten or twelve hours at a time during our march from Yambuya to Fort Bodo, we had frequent local showers of short duration. When these latter fell we were sure that some lofty hill was in the neighbourhood, which had intercepted a portion of the vapour drifting easterly, and liquified it for the benefit of the neighbourhood. The rear-guard of the caravan was sometimes plunged in misery by a heavy rainfall while the pioneers were enjoying the effects of sunshine above their heads. It occurred at Mabengu Rapids, and at Engweddé. Being in the depths of the forest we could not see any sign of a hill, but such sudden showers betrayed the presence of one in the vicinity. When well away from these localities we would sometimes look behind down a straight stretch of river, and hilly masses 500 feet above the river were revealed to us.
The Ituri or Upper Aruwimi is therefore seldom very low. We have seen it in July about six feet below high-water mark. In October one night it rose a foot; it is highest in November, and lowest in December. But it is a stream that constantly fluctuates, and pours an immense volume of water into the Congo. In length of course it is about 700 miles, rising to the south of that group of hills known as the Travellers’ Group, and called Mounts Speke, Schweinfurth, and Junker. Its basin covers an area of 67,000 square miles.