This pyramid is known historically to have been built by the order of King Cheops (or Khufu), and the date of its design and erection can be pretty accurately fixed as about 3700 B.C., or nearly 2,000 years earlier than that of the civilisation depicted in the Indian and Greek epics. The internal structure of this pyramid is its most interesting feature, because it shows clearly that it was designed to be not only the tomb of the king who built it, but also a true astronomical observatory during his life. This has been denied by some modern historians. In Harmsworth's _History of the World_ (p. 2034) it is said: "For the pyramids are nothing but tombs. They have no astronomical meaning or intention whatever." And then, after referring to the ideas of Piazzi Smyth and others as "vain imaginings," it is added: "There is nothing marvellous about these great tombs, except their size and the accuracy of their building." An almost exactly similar statement is made in the great _Historian's History of the World_, and in "Chambers's Encyclopædia." If the writers of these histories had read Mr. R. A. Proctor's book, _The Great Pyramid: Observatory, Tomb and Temple_, they would have known that this statement is entirely erroneous. The size, shape, and angles of the internal passages have been described and measured by many competent students, among the most careful and exact of whom was Piazzi Smyth, then Astronomer Royal of Scotland. It is true he had many "vain imaginings," but his measurements were among the most trustworthy. The "pyramid religion," which he helped to establish by a series of "coincidences" in the dimensions of various parts of the pyramid with astronomical dimensions, of which the pyramid builders could have had no knowledge whatever (such as the distance of the sun, the precession of the equinoxes, etc.), was no doubt a "vain imagining," but he frankly claimed it as a divine inspiration. All these are rejected by Mr. Proctor, who clearly explains the purpose of the greater part of the internal structure as only an experienced practical astronomer could do. I will now state as briefly as possible what are the well-established facts, as well as the conclusions at which Mr. Proctor arrives.