s. Europeans in general, like the ancient
Egyptians, place the commencement of the civil day at midnight, and reckon
twelve morning hours from midnight to midday, and twelve evening hours from
midday to midnight. Astronomers, after the example of Ptolemy, regard the
day as commencing with the sun's culmination, or noon, and find it most
convenient for the purposes of computation to reckon through the whole
twenty-four hours. Hipparchus reckoned the twenty-four hours from midnight
to midnight. Some nations, as the ancient Chaldeans and the modern Greeks,
have chosen sunrise for the commencement of the day; others, again, as the
Italians and Bohemians, suppose it to commence at sunset. In all these
cases the beginning of the day varies with the seasons at all places not
under the equator. In the early ages of Rome, and even down to the middle
of the 5th century after the foundation of the city, no other divisions of
the day were known than sunrise, sunset, and midday, which was marked by
the arrival of the sun between the Rostra and a place called Graecostasis,
where ambassadors from Greece and other countries used to stand. The Greeks
divided the natural day and night into twelve equal parts each, and the
hours thus formed were denominated _temporary hours_, from their varying in
length according to the seasons of the year. The hours of the day and night
were of course only equal at the time of the equinoxes. The whole period of
day and night they called [Greek: nuchthemeron].

_Week._--The week is a period of seven days, having no reference whatever
to the celestial motions,--a circumstance to which it owes its unalterable
uniformity. Although it did not enter into the calendar of the Greeks, and
was not introduced at Rome till after the reign of Theodosius, it has been
employed from time immemorial in almost all eastern countries; and as it
forms neither an aliquot part of the year nor of the lunar month, those who
reject the Mosaic recital will be at a loss, as Delambre remarks, to assign
it to an origin having much semblance of probability. It might have been
suggested by the phases of the moon, or by the number of the planets known
in ancient times, an origin which is rendered more probable from the names
universally given to the different days of which it is composed. In the
Egyptian astronomy, the order of the planets, beginning with the most
remote, is Saturn, Jupiter, Mars, the Sun, Venus, Mercury, the Moon. Now,