Let us suppose, for the sake of illustration, that it were agreed to abandon the Gregorian system of reckoning at a given moment, and to adopt another; that it were agreed to abandon it at all points on the globe when the hour should be twelve o’clock at noon at Greenwich, on the first day of January, 1885; and let us suppose that for historical or scientific purposes we were interested in knowing exactly how long the Gregorian system had been in use.  Is it possible to ascertain this?  It is; and very easily.  Using that system of universal time-reckoning which it is proposed to establish, but logically referring it to the origin of that cosmopolitan reckoning which really exists, that is to say, to the anti-meridian of Rome, we shall find that 1885 years have been reckoned according to the Gregorian system, plus the difference of longitude between the anti-meridians of Greenwich and Rome.  Nothing is more certain than this, and there is no other way of solving the problem.  As I have already shown, when the Gregorian correction was made, the day which, according to the old mode of reckoning, would have been the 5th of October, was called the 15th of October, 1582; the countries situated to the east of Rome had, however, previously begun to reckon according to the new system (previously in absolute time I mean,) and the countries situated to the west adopted it successively afterwards.  Now, then, as that portion of the globe which lies to the east of any given point or meridian is nothing more or less than one hemisphere, and as that which lies to the west is another hemisphere, it is evident that, at the anti-meridian of Rome, the two meridians, which constantly differ by one day in their dates, are confounded, and that the anti-meridian of Rome, being the first one in the world that adopted the Julian and the Gregorian systems of reckoning, is the prime meridian of the world, the meridian by which we now reckon, and ought to reckon universal time, until the establishment of a different system.  If we had, at the present time, to settle any question depending on dates, in the region where there is some confusion in regard to them, we should have to do so on this principle.  If we desired to compel the entire world to keep a regular and logical account of dates, we should have to do so by compelling all the nations to the west of the anti-meridian of Rome to go on reckoning their dates uninterruptedly after they have begun to be reckoned at the said anti-meridian, and by forbidding all the nations to the east of it to reckon any date until it has been reckoned at the anti-meridian of Rome.  For this reason I say that the express designation, for the reckoning of universal time, of the meridian of Greenwich or of any other than the anti-meridian of Rome, involves a chronological reform, inasmuch as it will involve the abandonment of the system to which we now adhere, and which we now use by common consent.