Prime Meridian

“ A very natural pride has led the great nations to establish by law their own prime meridian within their own borders, and into this error the United States was led about 35 years ago.
Should any of us now hesitate in the adoption of a particular meridian, or should any nation covet the honor of having the selected meridian within its own borders, it is to be remembered that when the prime meridian is once adopted by all it loses its specific name and nationality, and becomes simply the Prime Meridian. ”

“ In my own profession, that of a seaman, the embarrassment arising from the many prime meridians now in use is very conspicuous, and in the valuable interchange of longitudes by passing ships at sea, often difficult and hurried, sometimes only possible by figures written on a black-board, much confusion arises, and at times grave danger. In the use of charts, too, this trouble is also annoying, and to us who live upon the sea a common prime meridian will be a great advantage. ”

“ Being charged to maintain before you, gentlemen, the principle of the neutrality of the prime meridian, it is evident that if that principle was rejected by the Congress it would be useless for us to take part in the further discussion of the choice of the meridian to be adopted as the point of departure in reckoning longitude. ”

“ To resume, I would say that the great benefits that the whole world will receive from the adoption of a common prime meridian will not be fully produced unless the measure is unanimously accepted by all the most important maritime nations. ”

“ The inconvenience of east and west longitudes, which results [Pg 40] from having the prime meridian pass through a thickly populated portion of the world, will be removed by reckoning the longitude continuously from O° to 360°. At the same time an important advantage is secured by having the prime meridian occupy a central position with regard to the most densely populated part of the earth; because the distances which will then separate the various points from the central observatory marking the initial meridian will be a minimum, and consequently less liable to error in determination. ”

“ 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. ”

“ The advantage of drawing the prime meridian through the ocean has always been understood, and it was precisely for this reason that Marinus of Tyre, during the first century, placed it at the Fortunate Isles, west of the African Continent. It is idle to urge the difficulty of fixing such a meridian as an objection. Astronomy is so far advanced in our day as to enable us to make this calculation with all desirable accuracy. ”

“ 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. ”

“ Now, if any event which is taking place, or has taken place at any past time in the history of the world, is referred to the prime meridian, or is expressed in the time of any locality or of several localities, these times will all be different. The adoption of the universal day is to avoid any difficulty of that sort, and any event which has transpired will, when expressed in the time of the universal day—that is, according to the universal method—represent exactly the interval of time which has elapsed since the beginning of the Christian era. Nothing is gained or lost. ”

“ Other States, equally important by their merchant marine, especially the United States, make use of the Greenwich meridian. Well, gentlemen, if we weigh these reasons—the only ones that have been set forth, the only ones that at present militate for the Greenwich meridian—is it not evident that these are material superiorities, commercial preponderances that are going to influence your choice? Science appears here only as the humble vassal of the powers of the day to consecrate and crown their success. But, gentlemen, nothing is so transitory and fugitive as power and riches. ”

“ Right ascension is measured on the celestial equator, precisely the same as longitude on the earth, excepting that it is always measured eastward through the full 24 sidereal hours, contrary to the diurnal movement of heavenly bodies. Moreover, the meridian passing through the vernal equinox is called the celestial prime meridian, and sometimes the Greenwich of the heavens. There is another point of distinction, however, between this prime meridian of the sky and our meridian of Greenwich, which, while it does not effect practical navigation, has to receive consideration in the long run ”

“ I say certainly, because the result of the former votes being already known, it cannot be doubted on which side the majority will be, and because, from a scientific point of view, having chosen Greenwich as the prime meridian for the calculation of longitude, and having decided to reckon longitude in two directions from zero hours to twenty-four hours, with the sign plus towards the east and minus towards the west, it will be advantageous to make the civil day of Greenwich coincide with the universal day, if we would have an easy formula for passing from local to cosmic time. ”

“ To select as a prime meridian one which shall be a defined angular distance from one of the national meridians, must have for its object either to remove some inconvenience which results from the use of the national meridian itself, or it must be to satisfy a desire to deprive the selected meridian of any nationality. ”

“ Because if [Pg 126] you go on reckoning from zero to 360 degrees continuously, you have to make a break at 360 degrees. You do not count on after you have completed one revolution, but have to drop the 360 degrees and start again at zero. But this is attended with great inconvenience, because this break in counting occurs in countries which are thickly inhabited. The longitude would be a little less than 360 degrees on one side of the prime meridian, and on the other side the longitude would be a small angle. ”

“ Janssen, Delegate of France, said:
My eminent colleague, whose presence is an honor to this Congress, Professor Adams, thinks that I overlook too much the practical side of the question; namely, how a prime meridian can be established so as to cause the least inconvenience. He says that I pay too much attention to what he calls a question of sentiment, and he concludes by expressing the hope that all nations will lay aside their national pride and only be guided by this consideration: What meridian offers the greatest practical advantages? ”

“ If, on the contrary, any conclusion is to be drawn from the instructive debate at which we have assisted, it is that the principal, I will say more, the only merit of the Greenwich meridian—and our colleague from Great Britain just now reminded us of it by enumerating with complacency the tonnage of British and American shipping—is that there are grouped around it, interests to be respected, I will acknowledge it willingly, by their magnitude, their energy, and their power of increasing, but entirely devoid of any claim on the impartial solicitude of science. ”

“ 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. ”

“ But even if this difficulty were avoided, he could not see how they could have any place which would come within the definition of a neutral meridian. Supposing they took the Azores, they belong to Portugal; then certainly they would have a Portuguese prime meridian, belonging to the Portuguese nation. [Pg 62] Thus they would no longer have a neutral point, if he (Professor Newcomb) rightly understood the meaning of Professor Janssen. ”

“ That meridian passes, as I said before, outside of New Zealand, and outside of the Fijee Islands; it goes over only a very small portion of inhabited country. It appears to me, therefore, that inasmuch as there must be an absolute break or discontinuity in time in passing round the earth—a break of twenty-four hours—it is much more convenient that this break should take place in the uninhabited part of the earth than in the very centre of civilization. ”

“ In this view I trust the Conference will give some expression of opinion in favor of extending around the globe the system of hour meridians which has proved so advantageous in North America. In an educational aspect alone it seems to me important that the hour meridians, one to twenty-four, numbered from the anti-prime meridian continuously toward the west, should be conspicuously marked on our maps and charts. ”

“ Shall we introduce a new system, which may or may not be found practical or agreeable? Shall we not rather adopt the rule of all nations, already in use among their practised astronomers and navigators, by saying continue to do as you have already done?
Sir Frederick Evans, Delegate of Great Britain. Having for many years mixed among the practical seamen of more than one nation, I confess I look with some dismay on any other system for the notation of longitude being adopted than the one proposed in this resolution. ”

“ They are few in number compared with the rest of the world. They are intelligent, and could make the required change without any difficulty, and with very slight or no inconvenience.
The requisite changes in the astronomical and nautical ephemerides would be easily made. As these ephemerides are published several years in advance, there would be plenty of time for navigators to become familiar with the proposed change in time-reckoning before they were called upon to employ it in their calculations. ”

“ What is really determined is the longitude from some intermediate point, generally in the same country, and in telegraphic communication with the place whose longitude we wish to know. This intermediate point would, for the time, be the practical prime meridian. But the longitude of this point itself must always be uncertain. Science is continually advancing in accuracy, and we find that we continually need to correct the longitude of our intermediate meridian, and hence of all points determined from it. ”

“ For the present we decline the honor of immolating ourselves alone for progress of a problematic, and eminently secondary order; and it is with perfect tranquillity of conscience that we declare that we do not concur in the adoption of the meridian of Greenwich, persuaded as we are that France does not incur the reproach of retarding and of obstructing the march of science by abstaining from participating in this decision. ”

“ What I have to state is, that this method of absolute time-reckoning already exists, (although we do not use it,) as does this universal [Pg 159] meridian which has been tacitly chosen by almost all civilized nations—that is to say, by all such as have adopted the Julian calendar, with or without the Gregorian correction. ”

“ In the face of this difficulty, which appears to me insurmountable, the only solution which, by its very nature, will not raise exciting questions of national pride is that of a meridian having a character of absolute neutrality. If the adoption of such a meridian was admitted in principle, I am certain that a discussion based upon pure science, and following the best conditions which it should realize, would conduct us rapidly to a practical settlement of the question. ”

“ We should change the chronological reckoning which is now in vogue, and I contend that we have no right, scientific or historical, to make that change now. According to my views, the meridian of longitude is relatively an unimportant affair. It is a practical one; it cannot be changed in twenty years, probably, and it will take that time to correct all existing charts. But if you adopt a meridian for time, it will be very difficult to alter it in the future. ”

“ As a matter of economy, then, to the world at large, it would be better to permit those plates to remain unchanged which are engraved for the meridian of Greenwich and to make the necessary changes in all plates engraved for other meridians. ”

“ I ask, would the twenty-six nations here represented accept our recommendation to adopt the neutral meridian? I greatly fear that the passing of the resolution would not in the least promote the settlement of the important question before the Conference. The world has already at least eleven different first meridians. The adoption of the new meridian contemplated by the Delegates from France would, I apprehend, simply increase the number and proportionately increase the difficulty which so many delegates from all parts of the earth are assembled here to remove. ”

“ All this shows, gentlemen, how much wiser it would be to take for the origin of terrestrial longitude a point chosen from [Pg 50] geographical considerations only. Upon the globe, nature has so sharply separated the continent on which the great American nation has arisen, that there are only two solutions possible from a geographical point of view, both of them very natural.
The first solution would consist in returning, with some small modification, to the solution of the ancients, by placing our meridian near the Azores ”