ONE of the reasons why the Prime Meridian Conference met at Washington was that the United States possesses the greatest longitudinal extension of any country traversed by railway and telegraph lines, and it is quite in keeping with the spirit of American institutions that some of the most important measures necessary to carry out the resolutions of the Conference were taken by the railway men before the scientific men had begun their sittings. The action of the railway companies began as far back as 1883. It was a regular rebellion against the inconvenience of having more than half a hundred standards of railway time from east to west of the continent. At the Conference itself, Mr. W. F; Allen, one of the United States delegates, who has from the first taken the greatest interest in this special branch of the subject, brought the matter prominently before the Congress, stating what had been done. Since the Conference met, the suggestions primarily due to the railway authorities have been accepted by the Army Signal Corps and other public bodies, and from the east of Canada to the Pacific the Continent is now divided into five sections, each with its time standard, differing by one hour from those to the east and west. Thus we have Intercolonial time, Eastern time, Central time, Mountain time, and Pacific time, representing differences of one hour or 15° of longitude. We append a map, and a paper by Mr. Allen, which we have received from an esteemed correspondent, which will show at once the history of this movement and what has come of it.