A FISHING EXCURSION.--ENCOUNTERING A HIPPOPOTAMUS.--THE COUNTRY OF THE NYAM-NYAMS. The party was awake at an early hour, and there was no rest for anybody after daylight. The camp had been made close to a small lake that was said to abound in fish. One of the soldiers was an expert fisherman, and our friends were surprised to learn that they were to have fresh fish for breakfast. Frank asked Abdul how it happened, and the dragoman proceeded to enlighten him. [Illustration: ONE OF THE COOKS.] "You see," said Abdul, "that the lake where these fish were caught is the head of a small stream that runs into the Nile, and when it is full of water the fish run up from the river. They stay here and grow. Some of them are large enough when they leave the Nile, but, whether large or not, they are sure to grow bigger by staying in the lake." Fred wished to know what kind of fish they were. "There are several kinds," was the reply, "but the most important are the boulti and the baggera. They are a species of perch, and very fine eating. The boulti rarely weighs more than five pounds, but the baggera grows to an enormous size, and often exceeds a hundred pounds in weight. The largest I ever saw tipped the scale at a hundred and fifty-two pounds, but I have heard of their reaching two hundred and more. [Illustration: THE SECOND DAY'S MARCH.] "They may properly be called fishes of the Upper Nile and its tributaries. They are found in the Lower Nile, where they are hardly fit to eat. Travellers who have tasted them at Cairo and below the first cataract pronounce them worthless, but they should come here to eat them, where the flavor is delicious. The case is the same all the world over, and a fish that is excellent in one part of a river is worthless in another." "I can give you a good illustration of that," said the Doctor. "In Oregon the salmon ascend the Columbia River from the sea. The most of the fish continue up the Columbia, and the rest turn into the Willamette, a smaller river, on which Portland is situated. The salmon of the Columbia are considered among the finest of their species in the world, while those of the Willamette are of very poor quality. It is the same on the Colorado River: the fish of the upper part are excellent, while the same species lower down the stream are worthless. "We have an abundance for this morning, and it is a pity we cannot keep the surplus till we want it. They preserve the boulti here by splitting it down the back, salting it a few hours, and then smoking it over a wood fire. Thus prepared it will keep good a couple of days; but if it is wanted for a long time it must be smoked and dried in the sun till it is like a piece of board." Frank was curious to know how the fish were taken, and so it was arranged that he and Fred should accompany the fisherman on the first opportunity. It happened that very evening, as there was a lake near the second camp very much like the first.