feet thick, and is itself only three feet wide, and it
does not pass through the wall at right angles, but
cuts it somewhat obliquely, so that its axis is
roughly parallel to the meridian line.
A line drawn true north from the centre of the
arc at G will pass through the doorway of the small
temple and the centre of the arc kb at p. This line
points through the outer wall where the gap occurs,
and it is probable that the opening which was made
in the outer wall to allow of observation along this
line, determined its fall at this point. This meridian
line is thirty-six feet distant from the other from the
centre of the arc ak, and it must have pointed to
the same great stone. But if both these lines point
to the middle of this stone, which is 680 yards
distant, they will incline towards each other about
one degree, and the time of the O 7 transit of a star
over the stone observed by one line will differ four
minutes from that observed by the other. This
inaccuracy would be so obvious to the observers
that we cannot suppose they would have worked in
this way. The great stone measures nearly, if not
quite,' thirty-two feet across, and were the lines
directed, not both to its centre, but one to either side,
they would be parallel to each other and would both
give the same time for a transit of a star. This would
imply that stars were observed, not passing over the
stone, but disappearing and reappearing behind it,
and a star observed at the altar to disappear would
at the same instant reappear to an observer at Gr and
P ; or if the rock were less than thirty-two feet wide
W IT H IN T H E D O U B L E W A L L S . Z IM BA BW E