the distinction
which Prof. JANSSEN had attempted to establish between astronomical
and geographical longitude. It appeared to him that longitude was
longitude. It would never do if, for geographic purposes, we are to
have a second or third-class longitude and for astronomical purposes a
first-class longitude. He said that as a geographer he repudiated any
such idea. When you come to the practical application of the
determination of longitude at sea for maritime purposes, it is true
that a much less accurate determination suffices than would suffice
for the determination of longitude for astronomical observatories;
but, for all that, what is the object of a ship desiring to know what
its place at sea is? Obviously to arrive at the port to which it is
destined, and the object to be obtained is such a determination of the
longitude as to enable that ship to arrive at its port without danger.
You obtain a comparatively imperfect determination of longitude, but
it is sufficiently accurate to prevent you from striking on the solid
earth. But how is the longitude of the port to be determined?
Certainly, as has been properly said, by astronomical observations,
which can only be made with certainty on the earth. Consequently, it
seemed to him that it is absolutely essential for fixing an initial
meridian for the determination of longitude that it should be placed
at an astronomical observatory which can be connected with other
places by astronomical observations and by telegraph wires, and that
the idea of fixing a neutral meridian is nothing more than the
establishment of an ideal meridian really based upon some point at
which there is located an observatory. This has been repeated once or
twice before, and I need not enlarge upon it.

Prof. JANSSEN, Delegate of France. My honorable colleague, General
STRACHEY, thinks that longitude is longitude, and that there is not an
astronomical longitude and a geographical longitude. I answer, that
this is, nevertheless, what the nature of things indicates. The
longitude of observatories, or rather the difference of longitude
between those establishments, must be fixed with an accuracy which is
never sufficiently great. In the Bureau of Longitude of France we are
occupied with the differences of longitude of European observatories,
and we adopt for these calculations all the latest scientific
improvements, and especially the employment of electricity. Geography,
especially for general