Colonel Patterson had been ordered for service on the Uganda Railway, which runs from Mombasa north-westwards through British East Africa to the great lake Victoria Nyanza, the largest source-lake of the Nile. But in 1898, when the Colonel arrived, the railway had not been carried farther than the Tsavo, a tributary of the Sabaki, which enters the sea north of Mombasa. Here at Tsavo (see map, p. 237) the Colonel had his headquarters, and in the neighbourhood were camped some thousands of railway coolies from India. A temporary wooden bridge crossed the Tsavo, and the Colonel was to build a permanent iron bridge over the river, and had besides the supervision of the railway works for thirty miles in each direction. Some days after his arrival at Tsavo the Colonel heard of two lions which made the country unsafe. He paid little heed to these reports until a couple of weeks later, when one of his own servants was carried off by a lion. A comrade, who had a bed in the same tent, had seen the lion steal noiselessly into the camp in the middle of the night, go straight to the tent, and seize the man by the throat. The poor fellow cried out "Let go," and threw his arms round the beast's neck, and then the silence of night again fell over the surroundings. Next morning the Colonel was able to follow the lion's spoor easily, for the victim's heels had scraped along the sand all the way. At the place where the lion had stopped to make his meal, only the clothes and head of the unfortunate man were found, with the eyes fixed in a stare of terror. Disturbed by this sight and the sorrowful occurrence, the Colonel made a solemn oath that he would give himself no rest until both the lions were dead. Gun in hand, he climbed up into a tree close by his servants' tent and waited. The night was quiet and dark. In the distance was heard a roar, which came nearer as the two man-eaters stole up in search of another victim. Then there was silence again, for lions always attack in silence, though when they start on their night prowl they utter their hoarse, awful cry, as though to give warning to the men and animals in the neighbourhood. The Colonel waited. Then he heard a cry of terror and despair from another camp a hundred yards away, and after that all was still again. A man had been seized and dragged away. Now the Colonel chose a waiting-place where the last man had been carried off, but here, too, he was disappointed. A heart-rending shriek rang through the night at still another part of the camp, and another workman was missing.