But these extravagances have had the good effect of giving us accurate measurements of nearly all the dimensions of the Great Pyramid, and raising a great deal of discussion as to its aim and origin. In the first place it is quite clear that its primary object was to provide a royal tomb. A tomb of solid masonry with a base larger than Lincoln's Inn Fields, and 130 feet higher than St. Paul's, seems very incomprehensible to modern ideas, but there can be no doubt as to the fact. When the interior is explored both of this and other pyramids, nothing is found but one or two small sepulchral chambers containing the stone coffins of a king or queen. The Great Pyramid is not an exceptional monument, but one of a series of some seventy pyramid-tombs of kings, beginning with earlier and continued by later dynasties of the Old Empire. The reason of their construction is obvious. It originates from the peculiar ideas, which have been already pointed out, of the existence of a Ka or shadowy double, and a still more ethereal soul or spirit, whose immortality depended on the preservation of a material basis in the form of a mummy or likeness of the deceased person, preferably no doubt by the preservation of the mummy. This led to the enormous outlay, not by kings only, but by private persons, on costly tombs, which, as Herodotus says, were considered to be their permanent habitations. With an absolute monarchy in which the divine right of kings was strained so far that the monarch was considered as an actual god, it was only natural that their tombs should far exceed those of their richest subjects, and that unusual care should be taken to prevent them from being desecrated in future ages by new and foreign dynasties. Suppose a great and powerful monarch to have an unusually long and prosperous reign, it is quite conceivable that he should wish to have a tomb which should not only surpass those of his predecessors, but any probable effort of his successors, and be an unique monument defying the attacks not only of future generations, but of time itself.
This seems, without doubt, to have been the primary motive of the Great Pyramid, and in a lesser degree of all pyramids, sepulchral mounds, and costly tombs. But the pyramids, and especially the Great Pyramid, are not mere piles of masonry heaped together without plan or design. On the contrary, they are all built on a settled plan, which implies an acquaintance with the sciences of geometry and astronomy, and which, in the case of the Great Pyramid, is carried to an extent which shows a very advanced knowledge of those sciences, and goes far to prove that it must have been used, during part of the period of its construction, as a national observatory. The full details of this plan are given by Procter in his work on the Great Pyramid, and although the want of a more accurate knowledge of Egyptology has led him into some erroneous speculations as to the age and object of this pyramid, his authority is undoubted as to the scientific facts and the astronomical and geometrical conclusions which are to be drawn from them.
It appears that the first object of all pyramid builders was to secure a correct orientation; that is, that the four sides should face truly to the north, south, east, and west, or in other words that a line drawn through the centre of the base parallel to the sides should stand on a true meridian line. This would be a comparatively easy task with modern instruments, but before the invention of the telescope it must have required great nicety of observation to obtain such extremely accurate results in all the sides and successive layers of such an enormous building. There are only two ways in which it could be attempted—one by observing the shadow cast by a vertical gnomon when the sun was on the meridian, the other by keeping a standard line constantly directed to the true north pole of the heavens. In the case of the Great Pyramid another object seems to have been in view which required the same class of observations, viz. to place the centre of the base on the thirtieth degree of north latitude, being the latitude in which the pole of the heavens is exactly one-third of the way from the horizon to the zenith.
Both these objects have been attained with wonderful accuracy. The orientation of the Great Pyramid is correct, and the centre of its base corresponds with the thirtieth degree of north latitude within a slight error which was inevitable, if, as is probable, the Egyptian astronomers were unacquainted with the effect of atmospheric refraction in raising the apparent above the true place of celestial bodies, or had formed an insufficient estimate of its amount. The centre of the base is 2328 yards south of the real thirtieth parallel of latitude, which is 944 yards north of the position which would have been deduced from the pole-star method, and 3459 yards south of that from the shadow method, by astronomers ignorant of the effect of refraction. The shadow method could never have been so reliable as the polar method, and it is certain therefore à priori that the latter must have been adopted either wholly or principally, and this conclusion is confirmed by the internal construction of the pyramid itself, which is shown by the subjoined vertical section.
The tunnel A B C is bored for a distance of 350 feet underground through the solid rock, and is inclined at an angle pointing directly to what was then the pole-star, Alpha Draconis, at its lower culmination. As there is no bright star at the true pole, its position is ascertained by taking the point half-way between the highest and lowest positions of the conspicuous star nearest to it, and which therefore revolves in the smallest circle about it. This star is not always the same on account of the precession of the equinoxes, and Alpha Draconis supplied the place of the present pole-star about 3440 b.c., and practically for several centuries before and after that date.
Now the underground tunnel is bored exactly at the angle of 26° 17´ to the horizon, at which Alpha Draconis would shine down it at its lower culmination when 3° 42´ from the pole; and the ascending passage and grand gallery are inclined at the same angle in an opposite direction, so that the image of the star reflected from a plane mirror or from water at B, would be seen on the southern meridian line by an observer in the grand gallery, while another very conspicuous star in the southern hemisphere, Alpha Centauri, would at that period shine directly down it. The passages therefore would have the double effect, 1st, of enabling the builders to orient the base and lower layers of the pyramid up to the king's chamber in a perfectly true north and south line; 2nd, of making the grand gallery the equivalent of an equatorially-mounted telescope of a modern observatory, by which the transit of heavenly bodies in a considerable section of the sky comprising the equatorial and zodiacal regions, across the meridian, and therefore at their highest elevations, could be observed by the naked eye with great accuracy.
Those who wish to study the evidence in detail should read Procter's work on the Problems of the Pyramids, but for the present purpose it may be sufficient to sum up the conclusions of that accomplished astronomer. He says, "The sun's annual course round the celestial sphere could be determined much more exactly than by any gnomon by observations made from the great gallery. The moon's monthly path and its changes could have been dealt with in the same effective way. The geometric paths, and thence the true paths of the planets, could be determined very accurately. The place of any visible star along the zodiac could be most accurately determined."
If therefore the pyramid had only been completed up to the fiftieth layer, which would leave the southern opening of the great gallery uncovered, the object might have been safely assumed to be the erection of a great national observatory. But this supposition is negatived by the fact that the grand gallery must have been shut up, and the building rendered useless for astronomical purposes in a very short time, by the completion of the pyramid, which was then covered over by a casing of polished stone, evidently with a view of concealing all traces of the passages which led to the tomb. The only possible solution seems to be that suggested by Procter, that the object was astrological rather than astronomical, and that all those minute precautions were taken in order to provide not only a secure tomb but an accurate horoscope for the reigning monarch. Astrology and astronomy were in fact closely identified in the ancient world, and relics of the superstition still linger in the form of Zadkiel almanacs. When the sun, moon, and five planets had been identified as the celestial bodies possessing motion, and therefore, as it was inferred, life, and had been converted into gods, nothing was more natural than to suppose that they exercised an influence on human affairs, and that their configuration affected the destinies both of individuals and of nations. A superstitious people who saw auguries in the flight of birds, the movements of animals, the rustling of leaves, and in almost every natural occurrence, could not fail to be impressed by the higher influences and omens of those majestic orbs, which revolved in such mysterious courses through the stationary stars of the host of heaven. Accordingly in the very earliest traditions of the Accadians and Egyptians we find an astrological significance attached to the first astronomical facts which were observed and recorded. The week of seven days, which was doubtless founded on the first attempts to measure time by the four phases of the lunar month, became associated with the seven planets in the remotest antiquity, and the names of their seven presiding gods, in the same order and with the same meaning, have descended unchanged to our own times, as will be shown more fully in a subsequent chapter.