Then, his sensitive ears confirming the fact that the engine was no longer "knocking," he would lean back and gaze vacantly at an imaginary object yards in front, between the heads of the two occupants of the front seat, until symptoms of another mechanical eruption roused him into activity.
For several miles the road was fair, as far as African roads went. It had been constructed by forced labour under Hun supervision, and as such was made thoroughly and scientifically. But presently the road deteriorated into a mere track, rutted and impeded with stones and boulders. By a series of terrific gradients it climbed into what appeared to be impassable mountain fastnesses.
Sometimes it plunged through a rock-strewn kloof, then it swung dizzily round the shoulder of a precipitous rock. Sometimes it vanished under a sea of wind-ridged sand, to reappear in the guise of the bed of a long-dried-up mountain torrent.
"We're a good way from Kilembonga yet," observed Narfield. "It's a different type of country from this. I'm rather anxious to get into more civilised parts before nightfall."
Colin tried to make a suitable reply, but his teeth were chattering like castinets owing to the terrific bumping of the car. In spite of the cushions, he was feeling bruised all over.
Rather vaguely he wondered why men drove motor-cars in East Africa. Had the differential suddenly decided to part company and lie down in the road for a rest, Colin would not have been unduly surprised. It seemed marvellous that the swaying, jolting car held together.
"It's down hill for the next five miles," continued Colonel Narfield. "Look on your left; isn't that a fine bit?"
Colin did so. The road, slightly on the down grade, was working round the edge of an immense mass of rock, that rose almost sheer from the valley, a thousand feet below. The broad terrace—it was about twenty yards wide—in which the road ran, was the only track of any size on the face of the cliff, and, being partially overhung by the mass of rock beyond it and the summit, appeared narrower than it actually was. Beyond the valley, dense with sub-tropical foliage, and already shaded from the rays of the setting sun, were range upon range of rugged mountains.
Even as Sinclair was drinking in the magnificent grandeur of the panoramic view, there was a terrific report. For the moment Colin thought that one of the occupants of the back seat had discharged a rifle; but the next instant, as the car slithered and swung round at right angles to its original direction, he realised that a tyre had burst.
Then, with the almost instantaneous working of his brain, he was conscious of something to which the matter of a burst tyre was a mere nothing, for, with the engine still working and the clutch in, the car was heading straight for the brink of the precipice.