erally
interesting traits of their antiquity.

The _Astronomy_ of the American tribes, has been thought to merit
attention, in any attempts to compare them with foreign nations. The
evidences of the attainments of the ancient Mexicans in this science,
as well as the facts of their general history, chronology and
languages, have been examined by the venerable archaeologist and
ex-statesman, who presides over this society, in a critical
dissertation, published by the American Ethnological Society, which is
the ablest paper of the age. The results of Mr. Gallatin's labors, and
his reading of the ancient scrolls of Mexican picture writing,
preserved in the folios of Lord Kingsborough, while they limit the
amount of precise historical information in these unique records to
very narrow grounds, yet denote a degree of system and exactitude, both
in their chronology and astronomy, which are very remarkable.

The simple astronomy of our Aonic tribes of the north, gave them a
lunar year, consisting of twelve moons. They consequently had a year of
about three hundred and sixty days. As they had no names for days, no
week and no subperiods of a moon, but noticed and relied simply on the
moon's phases, they did not become acquainted with the necessity of
intercalations for the true length of the year. The Aztecs of Mexico,
on the contrary, had a solar year, and had made an extraordinary
advance in computing the true time. Their year consisted of eighteen
months, of twenty days each, a perfectly arbitrary system. This
division would give but three hundred and sixty days to the year. The
remaining five were called _empty_ or superfluous days, and were added
to the last month of the eighteen. A tropical year is, however, about
six hours longer than three hundred and sixty-five days, and by
throwing away six hours annually, there would be an entire day lost
every four years. The Mexican astronomers were well aware of this fact;
but instead of supplying the deficiency every fourth year as we do,
they disregarded it entirely, till a whole cycle consisting of
fifty-two years was completed, and then they intercalated thirteen
days, to make up the time and complete their cycle. In this way they
came to the same result as the Egyptians, but by a different process,
since the Egyptian calendar was founded on a computation of twelve
lunar months of thirty days each. It was precisely the same in the old
Persian calendar, which consisted of a ye