n the Mishna, dating from the second century
of our era, the appearance of the new moon at Jerusalem was signalled to
Babylonia during the century preceding the destruction of the Holy City
by Titus, and perhaps from earlier times. The dispersion of the Jews
had therefore presented them with an additional difficulty in fixing the
beginning of their months. The problem is much more intricate to-day,
seeing that the Jews are dispersed over the whole world, and the new
moon, first visible on one evening at Jerusalem, might be seen the
evening before, according to the reckoning of places west of Jerusalem,
or might be invisible until the following evening, according to the
reckoning of places east of it. We have the same problem to solve in
finding the date of Easter Sunday. The Prayer Book rule for finding it
runs thus:--

"Easter day is always the first Sunday after the full moon
which happens upon, or next after, the 21st day of March; and
if the full moon happens on a Sunday, Easter day is the Sunday
after."

But the "moon" we choose for the ecclesiastical calendar is an imaginary
body, which is so controlled by specially constructed tables as to be
"full" on a day not differing by more than two or three days at most
from the date on which the actual moon is full. This may seem, at first
sight, a very clumsy arrangement, but it has the advantage of defining
the date of Easter precisely, without introducing any question as to the
special meridian where the moon might be supposed to be observed. Thus,
in 1905, the moon was full at 4{h} 56{m} Greenwich mean time on the
morning of March 21. But Easter Day was not fixed for March 26, the next
Sunday following that full moon, but a month later, for April 23. For
the calendar moon, the imaginary moon, was full on March 20; and it may
be added that the actual moon, though full on March 21 for European
time, was full on March 20 for American time. There would have been an
ambiguity, therefore, if the actual moon had been taken, according to
the country in which it was observed, an ambiguity which is got rid of
by adopting a technical or imaginary moon.

The names given to the different months in Scripture have an interest of
their own. For the most part the months are simply numbered; the month
of the Passover is the first month, and the others follow, as the
second, third, fourth, etc., throughout the year; examples of each
occurring right up to the twelf