Of course many of the locusts fell on the deck of the steamer, and found their way to the cabins. The flight of the cloud was from south to north, and Frank observed a remarkable peculiarity about the movements of individual members of the immense swarm. He captured several and placed them on the cabin table. No matter in what direction he turned their heads, they immediately faced about towards the north, and as long as they were in the cabin they continued to try to escape on the northern side. After the boat had passed through the swarm, the boys released several of the captives, and found that, no matter how they were directed at the moment of their release, they immediately turned and flew away to the north. "They've one consolation," Fred remarked--"they have their compasses always about them, and have no need to figure up their reckoning with 'Bowditch's Navigator' to know which way to steer." "Don't you remember," Frank retorted, "our old teacher used to tell us that instinct was often superior to reason. Birds and animals and fishes make their annual migrations, and know exactly where they are going, which is more than most men could begin to do. These locusts are guided by instinct, and they are obliged to be, as they would starve if they had to reason about their movements, and study to know where to go. Just think of a locust sitting down to a map of China, when there were millions of other locusts all doing the same thing. They wouldn't have maps enough to go around; and when they got to a place they wanted to reach, they would find that others had been there before them and eaten up all the grass." Frank's practical argument about instinct received the approval of his friends, and then the topic of conversation was changed to something else. Both the boys were greatly interested in the various processes of work that were visible on shore. Groups of men were to be seen cutting reeds for fuel, or for the roofs of houses, where they make a warm thatch that keeps out the rain and snow. Other groups were gathering cotton, hemp, millet, and other products of the earth; and at several points there were men with blue hands, who were extracting indigo from the plant which produces it. The plant is bruised and soaked in water till the coloring-matter is drawn out; the indigo settles to the bottom of the tub, and the water is poured off; and after being dried in the sun, the cake forms the indigo of commerce. In many places there were little stages about thirty feet high, and just large enough at the top for one man, who worked there patiently and alone. Frank could not make out the employment of these men, and neither could Fred. After puzzling awhile over the matter, they referred it to Doctor Bronson. "Those men," the Doctor explained, "are engaged in making ropes or cables out of the fibres of bamboo." "Why don't they work on the ground instead of climbing up there?" Fred asked.