Proctor, Richard A.: The Great Pyramid: observatory, tomb, and temple (New York, 1883)

THE PROBLEM OF THE PYRAMIDS. 135

Now notice that the most important object of
transit observations is to determine the time at
which the objects observed cross the meridian.
Either the observer has to determine at what time
this happens, or, by noting when it happens, to
ascertain the time ; in one case, knowing the time,
he learns the position of the celestial object in what
is called right ascension (which may be called its
position measured around the celestial sphere in the
direction of its rotation); in the other, knowing the
position of the object in right ascension, he learns
the time, But whether the observer is doing one
or the other of these things, he must have a time-
indicator of some sort. Our modern astronomer
has his clock, beating seconds with emphatic thuds,
and he notes the particular thuds at or near which
the star crosses the so-called wires in the field of
view (really magnified spider lines). We may be
tolerably certain that the observer in the Grand
Gallery had no such horological instrument. But
he must have had a time-indicator of some sort
(and a good one, we may notice in passing), or the
care shown in the construction of the gallery would
have been in great part wasted.

Now, whence could his time-sounds have been
conveyed to him but from the upper end of the
gallery ? A time-measure of some sort—probably