On the afternoon of April 18, 1891, two trains met where only one was supposed to be. Fast Mail train No. 14 had the right of way on the Lake Shore & Michigan Southern's single track through Kipton, Ohio, forty miles west of Cleveland. The westbound Toledo Express, No. 21, was running late and was supposed to be waiting on the siding when No. 14 came through at speed. It was not. The two trains struck head-on. Nine people died, six of them postal clerks sorting mail in the forward cars.
Investigators found the Toledo Express crew was at fault: their train was already running behind schedule, and they pulled out for Kipton anyway, believing they could still clear the main line before the fast mail arrived. They could not. The inquiry centered on why: one of the crew's watches was found to be about four minutes off, enough on a schedule measured in single minutes to turn a routine meeting point into a collision.
The railroad's response was not simply to buy its crews better watches and leave it there. Soon after, the Lake Shore & Michigan Southern's general superintendent hired Webb C. Ball, a Cleveland jeweler, to overhaul how time was kept on the line. Ball required every conductor's and engineer's watch to be compared against a standard clock every two weeks, the result recorded on a card its owner carried; a watch that had gained or lost thirty seconds between inspections went in for repair. By 1893 the industry had drawn up a common specification for the watch itself: open-faced, a minimum of seventeen jewels, adjusted to five positions and to temperature, accurate to within thirty seconds a week. Most railroads adopted it, though not quickly — plenty kept accepting fifteen-jewel watches and three-position adjustment for another decade or more.
What changed at Kipton was not the reliability of any particular watch. It was whose word a railroad was willing to run on. A pocket watch that has never been checked against anything else can be wrong for months and never once contradict itself; the man carrying it has no way to know, and neither does anyone depending on him. A record updated every two weeks against a standard clock does not have that blind spot, because it does not depend on the watch's owner noticing his own error. It cannot tell you a watch is accurate. It can only tell you, on a fixed schedule, whether it still is.
Ball's inspection system went on to cover a reported hundred and twenty-five thousand miles of American track, but the part of it that mattered was never the watch itself. Any watch can drift. A schedule shared across a whole railroad cannot survive very many of its keepers finding that out on their own, after the fact, one collision at a time.