ccupies, in all, seventy-five pages--more than double that
taken up by the original explanation.

One of the first considerations which strikes us in comparing these
multitudinous publications is the confusion which must arise from the
use of so many meridians. If each of these southern nations, the
Spanish and Portuguese for instance, actually use a meridian of their
own, the practice must lead to great confusion. If their navigators do
not do so but refer their longitudes to the meridian of Greenwich, then
their almanacs must be as good as useless. They would find it far
better to buy an ephemeris referred to the meridian of Greenwich than
to attempt to use their own The northern nations, I think, have all
begun to refer to the meridian of Greenwich, and the same thing is
happily true of our own marine. We may, therefore, hope that all
commercial nations will, before long, refer their longitudes to one and
the same meridian, and the resulting confusion be thus avoided.

The preparation of the American Ephemeris and Nautical Almanac was
commenced in 1849, under the superintendence of the late Rear-Admiral,
then Lieutenant, Charles Henry Davis. The first volume to be issued was
that for the year 1855. Both in the preparation of that work and in the
connected work of mapping the country, the question of the meridian to
be adopted was one of the first importance, and received great
attention from Admiral Davis, who made an able report on the subject.
Our situation was in some respects peculiar, owing to the great
distance which separated us from Europe and the uncertainty of the
exact difference of longitude between the two continents. It was hardly
practicable to refer longitudes in our own country to any European
meridian. The attempt to do so would involve continual changes as the
transatlantic longitude was from time to time corrected. On the other
hand, in order to avoid confusion in navigation, it was essential that
our navigators should continue to reckon from the meridian of
Greenwich. The trouble arising from uncertainty of the exact longitude
does not affect the navigator, because, for his purpose, astronomical
precision is not necessary.

The wisest solution was probably that embodied in the act of Congress,
approved September 28, 1850, on the recommendation of Lieutenant Davis,
if I mistake not. "The meridian of the Observatory at Washington shall
be adopted and used as the American meridian for all astronom