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 astronomical purposes, and the meridian
of Greenwich shall be adopted for all nautical purposes." The
execution of this law necessarily involves the question, "What
shall be considered astronomical and what nautical purposes?"
Whether it was from the difficulty of deciding this question, or
from nobody's remembering the law, the latter has been practically
a dead letter. Surely, if there is any region of the globe which
the law intended should be referred to the meridian of Washington,
it is the interior of our own country. Yet, notwithstanding the
law, all acts of Congress relating to the territories have, so far
as I know, referred everything to the meridian of Greenwich and
not to that of Washington. Even the maps issued by our various
surveys are referred to the same transatlantic meridian. The
absurdity culminated in a local map of the city of Washington and