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, now, we absolutely wished for a physical point, we have the Island of St. Lawrence, which is cut towards its eastern part by such a meridian, and we could put a point of reference there, subject to the condition that the position of this point should conform to the definition, and that it should be removed, in one direction or the other, until it did conform to it. As to the very slight errors which might still affect the relative positions of the great observatories actually connected by electricity, they do not concern geography. If I am not mistaken, the eminent Superintendent of the American Nautical Almanac acknowledges that we could thus avoid the difficulties which might result from the changes to which the perfecting of science would in the course of time give rise in the statement of longitudes. In this manner the expense would be nothing or small. Thus, also, the meridian would be truly neutral, both by reason of its position in the ocean between the continents, and by reason of its definition, since the zero of longitude would then be so placed as to occupy a point not identified with any nation. This illustration appears to me to answer the demands of Professor NEWCOMB. I have taken it only for that reason, for I maintain no particular method, but only the principle of neutrality. Finally, I must return again to those sentimental reasons which my eminent and friendly opponents so often call to my attention. If I do not err, the very warmth of these interesting discussions shows me that the honor of being personally connected with a great reform touches us more than we are willing to admit, or than practical interests alone could effect.