Livingstone had plenty of work at the station. He built his house, he cultivated his garden, visited the sick, looked after his guns and waggons, made mats and shoes, preached, taught in his children's school, lectured on medicine, and instructed the natives who wished to become missionaries. In his leisure hours he collected natural history specimens, which he sent home, studied the poisonous tsetse fly and the deadly fever, and was always searching for remedies. He was never idle. His new place of abode had one serious defect--it was badly situated as regarded rain and irrigation, and therefore Livingstone decided to move again forty miles farther to the north, to Kolobeng, where for the third time he built himself a house. As before, his black friends were much disturbed at his departure, and when they could not induce him to remain, the whole tribe packed up their belongings and went with him. Then clearing, building, and planting went on again. At Kolobeng Livingstone had a fixed abode for quite five years, but this was his longest and last sojourn in one place, for his after-life was a continuous pilgrimage without rest and repose. As usual, he gained the confidence and friendship of the natives. The worst trouble was the vicinity of the Boers. They accused him of providing Sechele's tribe with weapons and exciting them against the Boers. They threatened to kill all black missionaries who ventured into the Transvaal, and devised plans for getting rid of Livingstone. Under such conditions his work could not be successful, and he longed to go farther north to countries where he could labour in peace without hindrance from white men who were nominally Christians, but treated the natives like beasts. Besides, hard times and famine now came to Kolobeng. The crops suffered from severe drought, and even the river failed. The natives went off to hunt, and the women gathered locusts for food. No child came to school, and the church was empty on Sunday. Then Livingstone resolved to move still farther northwards, and on June 1, 1849, the party set out. An Englishman named Oswell, who was Livingstone's friend, went with them and bore all the expenses of the journey. He was a man of means, and so several waggons, eighty oxen, twenty horses, and twenty-five servants were provided. After two months' march they came to the shore of Lake Ngami, which was now seen for the first time by Europeans. The king, Lechulatebe, proved less friendly than was expected. When he heard that Livingstone intended to continue his journey northwards to the great chief Sebituane, he feared that the latter would obtain firearms from the white men and would come down slaying and pillaging to the country round the lake. Finally the expedition was obliged to turn back to Kolobeng. Livingstone, however, was not the man to give in, and he went twice more to the lake, taking his wife and children with him.