吉萨金字塔The pyramid of Gizeh

14° The pyramid of Gizeh. The great pyramid of Gizeh was erected about 2900 B.C. and undoubtedly involved some mathematical and engineering problems.

The structure covers thirteen acres and contains over two million stone blocks, averaging two and a half tons in weight, very carefully fitted together. These stone blocks were brought from sandstone quarries located on the other side of the Nile. Some chamber roofs are made of fifty-four-ton granite blocks, twenty-seven feet long and four feet thick, hauled from a quarry six hundred miles away, and set two hundred feet above ground. It is reported that the sides of the square base of the pyramid involve a relative error of less than one fourteen thousandth, and that the relative error in the right angles at the corners does not exceed one twenty-seven thousandth.

Of course, the engineering skill implied by these impressive statistics is considerably diminished when we realize that the task was accomplished by an army of 100,000 laborers working for a period of thirty years. For example, the seemingly difficult problem of raising the great stone blocks to ever higher positions as the structure of the pyramid grew was probably very simply met by constantly keeping the rising pyramid submerged in imported sand, hauling the blocks on rollers up a gradual incline of this sand, and then finally removing all the imported sand. Given sufficient time and sufficient labor power, many difficult feats can be done in a simple and primitive fashion. Nevertheless, the engineering problems had to be overcome one way or another. Consider, for instance, the mammoth engineering problems encountered by the Egyptians in quarrying and setting up some of their huge obelisks of pink granite. The largest existing obelisk appears before the old Temple of the Sun at Thebes; it was quarried about 1500 B.C. and is no less than 105 feet long, nearly 10 feet square at the base, and weighs about 430 tons!