of longitude from geodetic measures, you must assume that the true figure and dimensions of the earth are known, which is far from being the case.  The theory that the prime meridian is a matter purely of a geographical nature is liable to the fatal objection that the determination of the difference of longitude between one place and the other is really the determination of the difference of time of the passage of a star across the meridian of the two places concerned.  That is very definite.  You observe the transit of the star at one place, and you observe the transit of the star at the other place, and by means of telegraphic communications you are able to determine their difference of longitude independent of the figure of the earth.  He said, in conclusion, that he thought the honorable Delegate of France was mistaken upon the main point which he had just referred to, if, indeed, he had rightly understood him.

M. JANSSEN, Delegate of France, replied as follows: 

I think that M. ADAMS entirely misunderstands me.  I agree with him absolutely in thinking that longitudes cannot be determined, especially of places far apart, except by astronomical methods.  Geodesy can only furnish it for short distances; in such cases, it is true, it supplies it with a degree of accuracy which meridianal observations cannot attain.  So, if the question be to determine rigorously the difference of longitude in time between two places on the earth at considerable distances apart, it becomes one of astronomy, because here it is astronomy which gives the quickest and most accurate solution.  For these reasons if, for instance, we should wish to connect a given observatory with a point situated on the other side of the ocean which had been chosen as the starting point of longitudes, it would become a question of astronomy.  Astronomy here is an admirable instrument for the solution, but it should only be the instrument.

On the contrary, the question becomes geographical, if it be that of determining where it will be most convenient to fix the origin of terrestrial longitudes.  If the question be, for instance, to select one or another point, in some one or other ocean, astronomy has nothing to do with it, and when it wishes to impose upon us one of its observatories to fulfil such a function it tends to give an inaccurate solution.

At first sight it may seem that any point might become a starting point for terrestial longitudes, but when we study the question a little more we see there may be great advantages in choosing some one point in preference to some other.  Hence it is that all geographers have agreed to place initial meridians, when possible, in the oceans.

The PRESIDENT stated that, in accordance with the decision of the Conference, he had sent to the scientists named by them invitations to a seat upon this floor.  The Chair sees several of these gentlemen here to-day, notably one of the most eminent astronomers of this country, to whom his countrymen are always ready to do homage, Professor Newcomb, Superintendent of the United States Nautical Almanac.  If it be the pleasure of the Congress, the Chair will now request Professor Newcomb to give us his views upon the resolution now under discussion.