Sir F. J. O. Evans, Delegate of Great Britain, then stated that he presumed the Conference could hardly pass by the important meeting held at Rome, where twelve of the thirty-eight Delegates were directors of national observatories, and where the subject of the conditions which should attach to a prime meridian were discussed without reference to any particular nationality; that these learned gentlemen came to the conclusion (which he thought was a very wise one) that the necessity existed for a prime meridian that it should pass through an astronomical observatory of the first order; that modern science demanded such precision, and therefore they excluded all ideas of a meridian being established on an island, in a strait, on the summit of a mountain, or as indicated by a monumental building. Looking at the subject in its various aspects, they came to the conclusion that there were only four great observatories which in their minds combined all the conditions, and this decision was unanimously received by that Conference. Those great observatories were Paris, Berlin, Greenwich, and Washington. He stated further that, having this in view, he thought this Conference should be particularly guarded, looking at the question from a scientific point of view, not to depart from the conditions laid down by the Conference at Rome; that he had no desire to advocate any one of the places enumerated, but merely mentioned them as satisfying all the conditions of science, which was so brilliantly represented at Rome.
Commander Sampson, Delegate of the United States, then said:
I can only attempt to anticipate the arguments which may be advanced by the learned Delegate from France in support of his resolution to adopt a neutral meridian. But it is our simple duty, in our present judicial capacity, to examine the question of a prime meridian from all points of view. With the object, then, of considering the question from another stand-point, I ask your attention for one moment. This Congress, at its last meeting, by a unanimous vote, declared its opinion that it was desirable to adopt a single prime meridian for the purpose of reckoning longitude. Further, it is fair to assume that the delegates here assembled, in answer to a specific invitation from the Government of the United States, and for a stated purpose, have come empowered by their respective governments to act upon the questions submitted for their consideration in the invitation.
At the last meeting, the Delegates from France left us somewhat in doubt regarding their views upon this important question of the powers of the delegates, or at least of their own delegation. But as they have to-day advocated the adoption of a neutral meridian, we may conclude that they have the necessary delegated power to fully consider and determine the main question before us—the selection of a prime meridian.
In the absence of any declared opinion to the contrary, we may take it for granted that the Delegates from all States here represented are deputed to "fix upon a meridian proper to be employed as a common zero of longitude throughout the globe," and to recommend the same for adoption to their respective Governments.
If, then, we are of one mind as to the desirability of a single prime meridian, and if we are fully empowered to make the selection, which may be taken as another way of saying that we are directed by our respective Governments to make the selection, we may proceed directly to the performance of this duty.
In the choice of a prime meridian, there is no physical feature of our earth which commends itself above others as the best starting point; nor does the form of the earth itself present any peculiarity which might be used as an initial point. If the refinements of geodesy should finally lead to the conclusion that the figure of the earth is an ellipsoid with three axes, yet the question of the direction of either of the equatorial axes must remain to such a degree uncertain that the extremity of the axis could not be assumed as the point of departure for counting longitude. Indeed, as an initial meridian must above all things be fixed in position, it would not answer to make its position depend upon any physical constant which is itself in the slightest degree uncertain; for in these days, when refinements in physical measurements are constantly leading to more and more accurate results, each advance in accuracy would necessitate an annoying change in the initial meridian, or, what would more probably result, the retention of the first chosen meridian, which would thus lose its dependence upon the original definition, and become as arbitrary as if taken by chance in the first instance.
We may then say that, from a purely scientific point of view, any meridian may be taken as the prime meridian. But from the standpoint of convenience and economy there is undoubtedly much room for a choice.
Considering this question of convenience in connection with the necessary condition of fixity already referred to, the prime meridian should pass through some well-established national observatory.
In making the choice of a prime meridian which is to serve for a great period of time, it is important to so fix and define it that the natural changes of time may not render it in the least degree uncertain. To this end, the nation within whose borders the chosen point may fall should engage to establish it in the most enduring manner, and protect it against all possible causes of change or destruction.