"In 1850," he continued, "very little was known of the Nile beyond the point reached by our enterprising countryman. Exploring parties had been up the river considerably beyond the Shillook region, but in most instances the explorers had died while beyond the limits of civilization, or their accounts were insignificant. For a long time it was supposed that the Blue Nile was the principal stream, and as its head-waters had been reached by the famous traveller Bruce, he was credited with the discovery of the sources of the mysterious river. But it was afterward found that the White Nile was the longer of the two and the greater in volume, and many lives were sacrificed in the attempt to find its origin. The discovery and exploration of the lakes of Central Africa, where the Nile rises, belongs to our day; and the names of Burton, Speke, Grant, Livingstone, Stanley, Baker, Long, and others, will go down in history for solving a mystery which has puzzled the world for centuries." One of the boys asked what they would have seen in case they had been able to ascend the Nile a few hundred miles farther? [Illustration: AN ARAB AND HIS CAMEL.] "That is a difficult question to answer," was the Doctor's reply, "but I will try to meet it. The second cataract is much like the first, and is a succession of rapids rather than a fall. It is two hundred and forty miles from Assouan to Wady Halfa, a village at the second cataract, and the point where nearly all tourists who go beyond here turn back. On the way thither you pass a few ruined temples and other remains of ancient Egypt; but there are none of great importance, with the exception of Abou Simbel, which ranks next after the pyramids and the temples of Thebes. There are two temples there hewn in the solid rock, and dating from the time of Rameses the Great. A good deal of the history of that monarch has been gathered from the sculptures in these temples, and the door-way of the principal one of them is guarded by a couple of enormous statues that recall the Sitting Colossi of Thebes. They have been pronounced the finest statues of their size in all Egypt, and certainly I do not know of any that can rival them in grandeur and beauty. [Illustration: COLOSSAL HEADS IN FRONT OF THE TEMPLE OF ABOU SIMBEL.] "These statues were formed by cutting away the solid rock, just as the statues of the temples of Ellora, in India, were made. Like most of the royal statues of Egypt, they represent the king seated on his throne. They are partly covered with the sand that has drifted about them, and sometimes little more than the heads of the figures are visible. They are said to be sixty-six feet high without their pedestals. A friend of mine measured the head of one of them, and gave me the following notes: Length of the nose, 3 feet 5 inches; height of the forehead, 28 inches; width of the mouth, 8 feet; length of the ear, 3 feet.