Part 15 (1/2)
With regard to the reckoning of longitude, I submit that longitude and time are so intimately related that they may be expressed by a common notation. Longitude is simply the angle formed by two planes pa.s.sing through the earth's axis, while time is the period occupied by the earth in rotating through that angle. If we adopt the system of measuring time by the revolution of the earth from a recognized zero, one of these planes--that through the zero--may be considered fixed; the other--that through the meridian of the place--being movable, the longitudinal angle is variable. Obviously the variable angle ought to be measured from the fixed plane as zero, and as the motion of the earth by which the equivalent time of the angle is measured is continuous, the longitude ought to be reckoned continuously in one direction. The direction is determined by the notation of the hour meridians, viz., from east to west.
If longitude be so reckoned and denoted by the terms used in the notation of cosmic time, the time of day everywhere throughout the globe would invariably denote the precise longitude of the place directly under the mean sun. Conversely, at the epoch of mean solar pa.s.sage at any place, the longitude being known, cosmic time would be one and the same with the longitude of the place.
The advantages of such a system of reckoning and nomenclature, as suggested in the recommendations which I now submit, will be, I think, self-evident.
RECOMMENDATIONS FOR THE REGULATION OF TIME AND THE RECKONING OF LONGITUDE
1. _That a system of universal time be established, with the view of facilitating synchronous scientific observations, for chronological reckonings, for the purpose of trade and commerce by sea and land, and for all such uses to which it is applicable._
2. _That the system be established for the common observance of all peoples, and of such a character that it may be adopted by each separate community, as may be found expedient._
3. _That the system be based on the principle that for all terrestrial time reckonings there be one recognized unit of measurement only, and that all measured intervals of time be directly related to the one unit measure._
4. _That the unit measure be the period occupied by the diurnal revolution of the earth, defined by the mean solar pa.s.sage at the meridian twelve hours from the Prime Meridian established through Greenwich._
5. _That the unit measure defined as above be held to be a day absolute, and designated a Cosmic Day._
6. _That such Cosmic Day be held as the chronological date of the earth, changing with the mean solar pa.s.sage at the anti-meridian of Greenwich._
7. _That all divisions and multiples of the Cosmic Day be known as Cosmic Time._
8. _That the Cosmic Day be divided into hours, numbered in a single series, one to twenty-four, (1 to 24,) and that the hours be subdivided, as ordinary hours, into minutes and seconds. Note.--As an alternative means of distinguis.h.i.+ng the cosmic hours from the hours in local reckonings, they may be denoted by the letters of the alphabet, which, omitting I and V, are twenty-four in number._
9. _That until Cosmic Time be admitted as the recognized means of reckoning in the ordinary affairs of life, it is advisable to a.s.similate the system to present usages and to provide for the easy translation of local reckonings into Cosmic Time, and vice versa; that, therefore, in theory, and as closely as possible in practice, local reckonings be based on a known interval in advance or behind Cosmic Time._
10. _That the surface of the globe be divided by twenty-four equidistant hour meridians, corresponding with the hours of the Cosmic Day._
11. _That, as far as practicable, the several hour meridians be taken according to the longitude of the locality, to regulate local reckonings, in a manner similar to the system in use throughout North America._
12. _That, in all cases where an hour meridian is adopted as the standard for regulating local reckonings, in a particular section or district, the civil day shall be held to commence twelve hours before and end twelve hours after the mean solar pa.s.sage of such hour meridian._
13. _That the civil day, based on the Prime Meridian of Greenwich, shall coincide and be one with the Cosmic Day.
That civil days on meridians east of Greenwich shall be (according to the longitude) a known number of hours, or hours and minutes in advance of Cosmic Time, and to the west of Greenwich the contrary._
14. _That the surface of the globe being divided by twenty-four equidistant meridians (fifteen degrees apart) corresponding with the hours of the Cosmic Day, it is advisable that longitude be reckoned according to these hour meridians._
15. _That divisions of longitude less than an hour (fifteen degrees) be reckoned in minutes and seconds and parts of seconds._
16. _That longitude be reckoned continuously towards the west, beginning with zero at the Anti-prime meridian, twelve hours from Greenwich._
17. _That longitude, generally, be denoted by the same terms as those applied to Cosmic Time._
I submit these recommendations suggestively, and without any desire unduly to press them. I shall be content if the leading principles laid down be recognized by the Conference.
With regard to the more immediate question, I have come to the firm conviction that extreme simplicity of reckoning and corresponding benefits would result if longitude be notated in the same manner, and denoted by the same terms as universal time. If, therefore, the Conference adopts the motion of the distinguished Delegate of the United States, which, I apprehend, is designed to cause as little change as possible in the practices of sea-faring men, I trust the claims of other important interests will not be overlooked. I refer to all those interests, so deeply concerned in securing accurate time on land, and in having easy means provided for translating any one local reckoning into any other local reckoning, or into the standard universal time. 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.
Prof. ADAMS, Delegate of Great Britain. I wish, Mr. President, to express my entire adhesion to the proposition which has been made by the Delegate of the United States, Mr. RUTHERFURD. It seems to me to satisfy one of the princ.i.p.al conditions that we have had before us to guide our decision; that is, that we should pursue a course which will produce the least possible inconvenience.
Now, I think if we keep that in mind, we shall have very little difficulty in coming to the conclusion that we should reckon longitude eastward, as positive or plus, and westward as negative or minus. This mode of reckoning would be attended with the least inconvenience; in fact, it will not be attended with any inconvenience at all, because it will keep to the present mode of reckoning. For my part, I see no adequate reason for changing that. There is no scientific reason, and certainly there is no practical reason. There is no scientific reason, because, as I stated yesterday, if in mathematics you measure from the zero a distance in one direction and consider that positive, you must, by the very nature of the case, consider the distance measured in the opposite direction from the same zero as negative. One follows mathematically and necessarily from the other, and by adopting this resolution you thus include both in one general formula.
It seems to me quite as scientific, to say the least, to start from zero and go in both directions, distinguis.h.i.+ng the longitudes by the signs plus and minus, according as the directions are taken east or west, as to reckon longitudes in one direction only from zero to 360 degrees. It is, I say, just as scientific to do this, and practically it is more convenient. Because if 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. This seems to me very inconvenient.