records no longer preserved. He says that one hundred and twenty
thousand men were employed in the construction of the largest
pyramid, and that, notwithstanding the size of this host of
workers, the task occupied twenty years. We must not place too
much dependence upon such figures as these, for the ancient
historians are notoriously given to exaggeration in recording
numbers; yet we need not doubt that the report given by Diodorus
is substantially accurate in its main outlines as to the method
through which the pyramids were constructed. A host of men
putting their added weight and strength to the task, with the aid
of ropes, pulleys, rollers, and levers, and utilizing the
principle of the inclined plane, could undoubtedly move and
elevate and place in position the largest blocks that enter into
the pyramids or--what seems even more wonderful--the most
gigantic obelisks, without the aid of any other kind of mechanism
or of any more occult power. The same hands could, as Diodorus
suggests, remove all trace of the debris of construction and
leave the pyramids and obelisks standing in weird isolation, as
if sprung into being through a miracle.


ASTRONOMICAL SCIENCE

It has been necessary to bear in mind these phases of practical
civilization because much that we know of the purely scientific
attainments of the Egyptians is based upon modern observation of
their pyramids and temples. It was early observed, for example,
that the pyramids are obviously oriented as regards the direction
in which they face, in strict accordance with some astronomical
principle. Early in the nineteenth century the Frenchman Biot