Similar remarks would apply to observations of the moon, which could also be directly observed. The planets and stars of course could only be observed directly.
The grand gallery could be used for the observation of any celestial body southing higher than 26° 18' above the horizon; but not very effectively for objects passing near the zenith. The Pleiades could be well observed. They southed about 63-2/3° above the horizon in the year 2140 B.C. or thereabouts when they were on the equinoctial colure.[46] But if I am right in taking the year 3300 B.C. when Alpha Centauri shone down the smaller ascending passage in southing, the Pleiades were about 58° only above the horizon when southing, and therefore even more favourably observable from the great meridional gallery.
In passing I may note that at this time, about 3300 years before our era, the equinoctial point (that is, the point where the sun passes north of the equator, and the year begins according to the old manner of reckoning) was midway between the horns of the Bull. So that then, and then alone, a poet might truly speak of spring as the time
"Candidus auratis aperit quum cornibus annum
Taurus."
as Virgil incorrectly did (repeating doubtless some old tradition) at a later time. Even Professor Smyth notices the necessity that the pyramid gallery should correspond in some degree with such a date. "For," says he, "there have been traditions for long, whence arising I know not, that the seven overlappings of the grand gallery, so impressively described by Professor Greaves, had something to do with the Pleiades, those proverbially seven stars of the primeval world," only that he considers the pyramid related to memorial not observing astronomy, "of an earlier date than Virgil's." The Pleiades also, it may be remarked, were scarcely regarded in old times as belonging to the constellation of the Bull, but formed a separate asterism.
The upper end of the great gallery lies very near the vertical axis of the pyramid. It is equidistant, in fact, from the north and south edges of the pyramid platform at this level, but lies somewhat to the east of the true centre of this platform. One can recognise a certain convenience in this arrangement, for the actual centre of the platform would be required as a position from whence observation of the whole sky could be made. Observers stationed there would have the cardinal points and the points midway between them defined by the edges and angles of the square platform, which would not be the case if they were displaced from the centre. Stationed as they would be close to the mouth of the gallery, they would hear the time signallings given forth by the observers placed at various parts of the gallery; and no doubt one chief end of the exact time-observations for which the gallery was manifestly constructed, would be to enable the platform observers duly to record the time when various phenomena were noticed in any part of the heavens.
This corresponds well with the statement made by Proclus, that the pyramids of Egypt, which, according to Diodorus Siculus, had been in existence during 3600 years, terminated in a platform upon which the priests made their celestial observations. The last-named historian alleges, also (Biblioth. Hist. Lib. I.), that the Egyptians, who claimed to be the most ancient of men, professed to be acquainted with the situation of the earth, the risings and settings of stars, to have arranged the order of days and months, and pretended to be able to predict future events, with certainty, from their observations of celestial phenomena. I think that it is in this association of astrology with astronomy that we find the explanation of what, after all, remains the great mystery of the pyramid—the fact, namely, that all the passages, ascending, descending, and horizontal, constructed with such extreme care, and at the cost of so much labour, in the interior of the great pyramid, were eventually (perhaps not very long after their construction) to be closed up. I reject utterly the idea that they could have been constructed merely as memorials. Sir E. Beckett, who seems willing to admit this conception, rejects the notion that the builders of the pyramid recorded "standard measures by hiding them with the utmost ingenuity." Is it not equally absurd to imagine that they recorded the date of the great pyramid, by construction, by those most elaborately concealed passages? Why they should have concealed them after constructing them so carefully, may not be clear. For my own part, I regard the theory that the Pyramid of Suphis was built for astrological observations, relating to the life of that monarch only, as affording the most satisfactory explanation yet advanced of the mysterious circumstance that the building was closed up after his death. Supposing the part of the edifice (fifty layers in all), which includes the ascending and descending passages, to have been erected during his lifetime, it may be that some reverential or superstitious feeling caused his successors, or the priesthood, to regard the building as sacred after his death—to be closed up therefore and completed as a perfect pyramid, polished ad unguem from its pointed summit to the lines along which the four faces met the smooth pavement round its base. We might thus explain why each monarch required his own astrological observatory afterwards to become his tomb. Be this as it may, it is certain that the pyramids were constructed for astronomical observations; and it would, I conceive, be utterly unreasonable to imagine that the costly interior fittings and arrangements, "not inferior, in respect of curiosity of art or richness of materials, to the most sumptuous and magnificent buildings," were intended to subserve no other purpose but to be memorials; and that, too, not until, in the course of thousands of years, the whole mass of the pyramid had begun to lose the exactness of its original figure.