material carrying these diagonal joints
was harder and better than elsewhere in the floor, so as to have
saved that part from the monstrous excavations elsewhere
perpetrated by some moderns. Why, then, did the builders change the
rectangular joint angle at that point, and execute such unusual
angles as they chose in place of it, in a better material of stone
than elsewhere; and yet with so little desire to call general
attention to it, that they made the joints fine and close to that
degree that they escaped the attention of all men until 1865 A.D.
The answer came from the diagonal joints themselves, on discovering
that the stone between them was opposite to the butt end of the
portcullis of the first ascending passage, or to the hole whence
the prismatic stone of concealment through 3000 years had dropped
out almost before Al Mamoun's eyes. Here, therefore, was a secret
sign in the pavement of the entrance-passage, appreciable only to a
careful eye and a measurement by angle, but made in such hard
material that it was evidently intended to last to the end of human
time with the great pyramid, and _has_ done so thus far."

Whether Professor Smyth is right in considering that this
specially-prepared position of the floor was intended not for any
practical purpose, but to escape the notice of the careless, while yet,
when the right men "at last, duly instructed, entered the passage," this
mysterious floor-sign should show them where a ceiling-stone was
movable, on perceiving which they "would have laid bare the beginning of
the whole train of those sub-aerial features of construction which are
the great pyramid's most distinctive glory, and exist in no other
pyramid in Egypt or the world," I leave the reader to judge. I would
remark, only, that, if so, the builders of the pyramid were not
remarkably good prophets, seeing that the event befell otherwise, the
ceiling-stone dropping out a thousand years or so before the floor-sign
was noticed; wherefore we need not feel altogether alarmed at their own
prediction (according to Professor Smyth), that the end of the world is
to come in 1881, even as Mother Shipton also is reported to have
prophesied. For my own part, I am quite content with my own
interpretation of the secret sign; as showing where the floor of the
descending passage was purposely prepared for the reception of water, on
the sti