asks me to point out the advantages of a neutral
meridian. These advantages are of two kinds--they are of a
geographical nature and a moral nature. Let us examine the first. By
placing the initial meridian between Asia and America, we get away
from the centres of population, which is almost indispensable in view
of the change of dates. We divide the world into two parts, the Old
World and the New. The advantage of drawing the prime meridian
through the ocean has always been understood, and it was precisely for
this reason that Marinus of Tyre, during the first century, placed it
at the Fortunate Isles, west of the African Continent. It is idle to
urge the difficulty of fixing such a meridian as an objection.
Astronomy is so far advanced in our day as to enable us to make this
calculation with all desirable accuracy.

As to the methods of obtaining this meridian exactly, there are
several. I have already spoken of them, but I return to the subject,
since more details are desired. These methods fall under two principal
heads. We can, and that is the ancient idea, choose some remarkable
physical point--as, for instance, the extremity of an island, a
strait, the summit of a mountain--and determine approximately the
distance in longitude of this point from the points of reference,
which are at present the observatories. This method, if all the
precision that science can now attain is required, would be costly in
certain cases. For the Azores the expense would be small, because of
the proximity of the telegraphic cables; it would be much greater for
Behring Straits. On the hypothesis of the employment of this method,
it would evidently be necessary to place our meridian at the Azores.

According to the other method, it is not the physical point which is
fixed, but simply the distance of the assumed origin from the points
of comparison. For example, admit that the general definition of our
prime meridian was that it should pass through the middle of Behring
Straits. To obtain its theoretical definition, we should obtain a
position of this point, either by summary observations of the nature
of hydrographic surveys, or by the aid of existing information, and
the longitude thus obtained would be connected with the observatories
best connected with each other. A list of the differences of longitude
would become the definition of our meridian, and not the physical
point in the sea which marks the exact middle of the strait. If, no