Do you want a striking example of what differentiates a neutral meridian from a national meridian?  In order to avoid the confusion which existed in geography at the beginning of the seventeenth century, on account of the multiplicity of initial meridians then in use, a congress of learned men, assembled in Paris at the instance of Richelieu to select a new common meridian, fixed its choice on the most eastern point of the Island of Ferro.  This was a purely geographical meridian, being attached to no capital, to no national observatory, and consequently neutral, or, if you please, purely geographical.  Later, Le pere Feuillet, sent in 1724 by the Academy of Sciences to determine the exact longitude of the initial point, having given the figure 19 deg. 55’ 3” west of Paris, the geographer, Delisle, for the sake of simplicity, adopted the round number 20 deg.; and, as I stated a little while ago, this alteration completely changed the character of this prime meridian.  It ceased to be neutral, and became merely the meridian of Paris disguised, as has been truly said, and the English, notably, never adopted it.  Here is the difference, gentlemen, between a neutral meridian and a national meridian.

And, parenthetically, you see, gentlemen, how dangerous it is to awaken national susceptibilities on a subject of a purely scientific nature.  Now allow me to add that, if in 1633 it was possible to find a neutral meridian, a purely geographical meridian, an independent meridian, it may easily be done in 1884 if we wish to do so; and that a point chosen on purely geographical considerations, either in Behring’s Strait or in the Azores, could be much better determined now than was possible to Father Feuillet in 1724, and could take the position which the meridian of Ferro would not have lost had it not been confounded with the meridian of Paris.

Professor J. C. ADAMS, Delegate of Great Britain, stated that he merely desired to refer to one subject touched on by the Delegate of France, Mr. JANSSEN, whose opinion he thought could hardly be supported, and that was that the question of longitude was purely one of geography.  He desired to controvert that, and to hold that the question of longitude was purely one of astronomical observation.  The difference of longitude between two places could not be determined by geodetic observations, because to do this you must take hypothesis as to the figure of the earth, and the figure of the earth is not a simple figure.  You may take as hypothesis that the figure of the earth is spheroidal, and that the ratio of the axes is exactly defined.  Now, in the first place, we are not agreed as to the exact ratio of the axes, nor are we agreed as to the exact figure of the earth.  If an attempt is made to measure the difference of longitude between two points on the earth’s surface, especially when they are a considerable distance from each other, it is necessary to depend upon astronomical observations.  In attempting to deduce the difference