the sun himself, drawing with him the whole
planetary system, completes an arc of his own
mighty orbit, about equal to the whole circuit
of the course of the earth. Accordingly, every
year appears to have included (as it does in
reality) the three hundred and sixty-sixth day.
But adhering strictly to the fact, the last solar
day of the old year was identical with the first
of the new, the day of "completion-beginning;"
except in every fourth or grand year, when
the earth's revolution being completed simul-
taneously, or very nearly simultaneously, with
a rotation, the two festivals became distinct.
Moreover, since four minutes (of time) a day,
amounts in the course of a year to the time
occupied by a complete rotation of the earth,
it follows that the number of such rotations
or sidereal days in each year exceeds by one
the solar days ; the difference being due to
the fact that the change in the earth's position
every twenty-four hours, owing to its orbital
motion, must be taken into consideration