Geoscience Reference
In-Depth Information
one meridian was chosen as the Prime Meridian, whatever the positive reasons to do
so, the others would feel lessened in importance. During the discussion, M. Levasseur,
one of the French representatives, generously said that had the discussion taken place
in the sixteenth or seventeenth century, the choice of Prime Meridian would naturally
have fallen on the Paris Meridian. But the majority of charts being used at that time
were based on the Greenwich Meridian and it had become the natural choice.
In 1875, a second International Geographical Conference in Rome re-opened the
matter and here France linked time and longitude to the issue of the standardization
of units. France would adopt the Greenwich Meridian if Britain would adopt the
metric system. Once again, the scientific and practical arguments were linked in
political negotiation.
The Americans took up the issue as a civil matter rather than as a scientific one,
driven by the practical problem of the range of longitude across the country (Bartky
2000). Charles Dowd of Saratoga Springs, NY, devised the present time zone system,
based on strips of longitude 15° wide, with a one hour increment in standard zone time
from one to the next. Cleveland Abbe of the Cincinnati Observatory became the first
official weather forecaster of the United States and found a uniform time system a
pressing need; he was therefore designated as the director of the US Signal Office to
do this. In 1876, Sandford Fleming of the Canadian Pacific Railway strongly argued
for a unified time that could be used across the world for railway, telegraph and scien-
tific purposes, and advocated the practical use of Dowd's time zone system.
In April 1883, the General Time Convention met in St. Louis to rationalize the
US railway time systems. Its secretary, a railway engineer named William F. Allen,
showed how to cluster railroad lines into groups to run on standard time zones. He
grouped the ten most widely used operating time standards into an eastern and a
western set and located the end points of the railway lines in each set. He calculated
the central meridian of each pair of extremes and found that they were almost
exactly an hour apart in time. He proposed that they be defined exactly as one hour
differences and added three more meridians, two in the western USA and one in
Canada's maritime provinces thus encompassing the remaining North American
railroads. He showed how in practice the one hour time zone shifts would occur
predominantly at the end points of the individual railroad systems so that passen-
gers would change time as they changed trains. He noted “a curious fact” that the
central meridian of the Eastern Time Zone coincided within six seconds with
the seventy-five degree meridian west of Greenwich, five hours from Greenwich time.
The American railroad delegates who argued against the use of a standard of time
kept at a distant European city were outnumbered by those who did not want
the choice to favor one of their US rivals and this removal of inter-city, inter-railroad
rivalry won the consensus. By the end of the year and under the commercial
imperative to rationalize railroad operation, Railroad Time was implemented on
this system, and by December 1884, all North American railroads except two small
ones around Pittsburgh had adopted it.
Not every one had the same pressing practical need to integrate longitude and
time systems. The British Astronomer Royal, George Airy, rejected the notion that
the government should interfere in such a social matter but said that if longitude
