For eighteen days no special incident occurred. The Makololos did not appear, and Mokoum, though still distrustful, exhibited fewer indications of alarm. They were not more than fifty miles from the desert; and the karroo was still verdant, and enriched by abundant water. They thought that neither man nor beast could want for any thing in this region so rich in game and pasturage; but they had reckoned without the locusts, against whose appearance there is no security in the agricultural districts of South Africa. On the evening of the 20th, about an hour before sunset the camp was arranged for the night. A light northerly breeze refreshed the atmosphere. The three Englishmen and Mokoum, resting at the foot of a tree, discussed their plans for the future. It was arranged that during the night the astronomers should take the altitude of some stars, in order accurately to find their latitude. Every thing seemed favourable for the operations; in a cloudless sky the moon was nearly new, and the constellations might be expected to be clear and resplendent. Great was the disappointment, therefore, when Emery, rising and pointing to the north, said,-- "The horizon is overcast: I begin to fear our anticipations of a fine night will hardly be verified." [Illustration: A strange Cloud.] "Yes," replied Sir John, "I see a cloud is rising, and if the wind should freshen, it might overspread the sky." "There is not another storm coming, I hope," interposed the Colonel. "We are in the tropics," said Emery, "and it would not be surprising; for to-night I begin to have misgivings about our observations." "What is your opinion, Mokoum?" asked the Colonel of the bushman. Mokoum looked attentively towards the north. The cloud was bounded by a long clear curve, as definite as though traced by a pair of compasses. It marked off a section of some miles on the horizon, and its appearance, black as smoke, seemed to excite the apprehensions of the bushman. At times it reflected a reddish light from the setting sun, as though it were rather a solid mass than any collection of vapour. Without direct reply to the Colonel's appeal, Mokoum simply said that it was strange. In a few minutes one of the Bochjesmen announced that the horses and cattle showed signs of agitation, and would not be driven to the interior of the camp. "Well, let them stay outside," said Mokoum; and in answer to the suggestion that there would be danger from the wild beasts around, he added significantly, "Oh, the wild beasts will be too much occupied to pay any attention to them." After the native had gone back, Colonel Everest turned to ask what the bushman meant; but he had moved away, and was absorbed in watching the advance of the cloud, of which, too accurately, he was aware of the origin.