Geoscience Reference
In-Depth Information
The problem of the misorientation of the telescope building was inconvenient,
but in other cases confusion about longitude might have been dangerous. For exam-
ple in the nineteenth century it was common for two ships that passed each other to
exchange estimates of position for comparison. This might be through large num-
bers written in chalk on a blackboard, possibly in poor visibility conditions, and
with little space or time for geodetic finesse. If there were opportunities for mis-
takes in the careful laying out of foundations, there would be even greater risks of
mistakes in the hurried and limited communications between ships. And what
might be the consequences if wrong information influenced a captain in the assess-
ment of his longitude at a later time in the voyage nearer to shore?
The same confusion was possible in analyzing scientific observations estab-
lished on time. Events such as eclipses or the variability of stars were observed in
time systems based on clocks kept at the local observatory, regulated by the passage
of the stars. Meteorological and magnetic observations were further examples of
sciences where timed observations were required. In order to gather, compare and
analyze such observations there had to be a system relating time frames and longi-
tude. This confusion had been noted by Pierre-Simon Laplace in 1800, who advo-
cated the world-wide unification of longitude and by John Herschel in 1828, who
advocated unification of time-keeping (Howse 1984).
Some progress was made in unifying timekeeping with the coming of the rail-
ways, which involved traveling long distances east-west while keeping to a schedule
drawn up accurately to the minute. Alongside the railway lines telegraph wires
were erected that carried pulses of electrical current which traveled all but instantly.
This made it possible to synchronize clocks at stations along the tracks, and there-
fore in a small country it became possible to distribute a national time system based
on observations at its national observatory; Britain distributed Greenwich Mean
Time (GMT) in this way. In larger countries with greater east-west extent such as
the United States, the railroads were run by separate owners over limited longitude
ranges, and the schedules were coordinated in separate time zones usually based on
the railway company's headquarters. In the United States in 1883, there were 49
separate railroad operating time systems. Additionally, submarine telegraph cables
made coordination necessary across oceans. The development of transcontinental
and intercontinental air travel was still in the future but this would only have added
weight to the requirement for a global time system.
THE FIRST OFFICIAL MOVE to unification was made in 1871 at the International
Geographical Conference in Antwerp. The Conference resolved that nautical charts
should be unified on the Greenwich Meridian and that communication between ships
should always provide longitude based this way - but not coastal or land charts; the
possession of a meridian had become a matter of national pride. In 1809 William
Lambert presented to the United States House of Representatives a memorandum stat-
ing that the calculation of longitude from the meridian of a foreign country implied a
degrading dependence and was a shackle of colonial dependence which remained an
encumbrance unworthy of the freedom and sovereignty of the American people; in
essence, the United States ought to have a meridian of its own. It was obvious that if
