ined as at
first defined. This was a real misfortune for geography. Our maps,
while being perfected, would have preserved a common unit of origin,
which, on the contrary, has altered more and more.

If, as soon as astronomical methods had been far enough advanced to
permit the establishment of relative positions with that moderate
accuracy which is sufficient for ordinary geography, (and that could
have been done at the end of the 17th century,) we had again taken up
the just and geographical conception of Marinus of Tyre, the reform
would have been accomplished two centuries sooner, and to-day we
should have been in the full enjoyment of it. But the fault was
committed of losing sight of the essential principles of the question,
and the establishment of numerous observatories greatly contributed to
this. Furnishing naturally very accurate relative positions, each one
of these establishments was chosen by the nation to which it belonged
as a point of departure for longitude, so that the intervention of
astronomy in these questions of a geographical nature, an intervention
which, if properly understood, should have been so useful, led us
further away from the object to be attained.

In fact, gentlemen, the study of these questions tends to show that
there is an essential distinction between meridians of a geographical
or hydrographical nature and meridians of observatories. The meridians
of observatories should be considered essentially national. Their
function is to permit observatories to connect themselves one with
another for the unification of the observations made at them. They
serve also as bases for geodetic and topographical operations carried
on around them. But their function is of a very special kind, and
should be generally limited to the country to which they belong.

On the contrary, initial meridians for geography need not be fixed
with quite such a high degree of accuracy as is required by astronomy;
but, in compensation, their operation must be far reaching, and while
it is useful to increase as much as possible the number of meridians
of observatories, it is necessary to reduce as much as we can the
starting points for longitudes in geography.

Further, it may be said that as the position of an observatory should
be chosen with reference to astronomical considerations, so an initial
meridian in geography should only be fixed for geographical reasons.

Gentlemen, have these two very different funct