inviolate until the day of resurrection, the embalmed bodies of their kings. The roofs of the burial chambers in the heart of the Pyramids were prevented from falling in, under the great weight of the superincumbent mass, by huge blocks, or beams, of the hardest granite, meeting at an angle above the chambers. The long galleries by which the chambers were approached were closed after the burial by enormous gates, consisting of blocks of granite, which were let down from above, sliding in grooves like the portcullis of a feudal castle. In this way it was hoped to preserve the corpse contained in the chamber absolutely inviolate. The huge blocks of granite, which weighed from 50 to 60 tons each, were supposed to be too heavy ever to be moved again after they had been once lowered into position, and they were so hard that it was believed they could never be pierced. Now, even if we had no other evidence to guide us, the existence of these blocks of granite in the Pyramids would afford the strongest presumption that the Egyptians of that remote time were perfectly familiar with the arts of inland navigation, for the stone was quarried at Assouan, close to the first cataract, 583 miles above Cairo, and could only have been conveyed from the quarry to the building site by water. In the neighbourhood of Memphis are hundreds of other blocks of granite from Assouan, many of them of enormous size. The Pyramid of Men-kau-Ra, or Mycerinus, built about 3633 B.C., was once entirely encased with blocks from Assouan. The Temple of the Sphinx, built at a still earlier date, was formed, to a large extent, of huge pieces of the same material, each measuring 15 x 5 x 3.2 feet, and weighing about 18 tons. The mausoleum of the sacred bulls at Sakara contains numbers of Assouan granite sarcophagi, some of which measure 13 x 8 x 11 feet. These are but a few instances, out of the many existing, from which we may infer that, even so far back as the fourth dynasty, the Egyptians made use of the arts of inland navigation. We are, however, fortunately not obliged to rely on inference, for we have direct evidence from the sculptures and records on the ancient tombs. Thanks to these, we now know what the ancient Nile boats were like, and how they were propelled, and what means were adopted for transporting the huge masses of building material which were used in the construction of the temples and monuments.