f rubbish which came from their work, and which Strabo looked so
particularly for 1800 years ago, but could not find. Here they were,
however, and still are, utilised in enabling the great pyramid to stand
on the very utmost verge of its commanding hill, within the limits of
the _two_ required latitudes, as well as over the centre of the land's
physical and radial formation, and at the same time on the sure and
proverbially wise foundation of rock.'

The next circumstance to be noted in the position of the great pyramid
(as of all the pyramids) is that the sides are carefully oriented. This,
like the approximation to a particular latitude, must be regarded as an
astronomical rather than a geographical relation. The accuracy with
which the orientation has been effected will serve to show how far the
builders had mastered the methods of astronomical observation by which
orientation was to be secured. The problem was not so simple as might be
supposed by those who are not acquainted with the way in which the
cardinal points are correctly determined. By solar observations, or
rather by the observations of shadows cast by vertical shafts before and
after noon, the direction of the meridian, or north and south line, can
theoretically be ascertained. But probably in this case, as in
determining the latitude, the builders took the stars for their guide.
The pole of the heavens would mark the true north; and equally the
pole-star, when below or above the pole, would give the true north, but,
of course, most conveniently when below the pole. Nor is it difficult to
see how the builders would make use of the pole-star for this purpose.
From the middle of the northern side of the intended base they would
bore a slant passage tending always from the position of the pole-star
at its lower meridional passage, that star at each successive return to
that position serving to direct their progress; while its small range,
east and west of the pole, would enable them most accurately to
determine the star's true mid-point below the pole; that is, the true
north. When they had thus obtained a slant tunnel pointing truly to the
meridian, and had carried it down to a point nearly below the middle of
the proposed square base, they could, from the middle of the base, bore
vertically downwards, until by rough calculation they were near the
lower end of the slant tunnel; or both tunnels could be made at the same
time. Then a subterranean chamber woul