Latitude, How American Astronomers Solved
the Mystery of Variation.
by
Bill Carter and Merri Sue Carter
The new constitutional democracy formed when America gained independence from
Britain had no system to support scientific research, and for most of its first century American
scientists lagged far behind their European colleagues. By the middle of the nineteenth century
the situation was so bad that a group of American scientists formed to raise the level of the
nation's scientific capabilities, led by Alexander Dallas Bache, a great grandson of Benjamin
Franklin, adopted the name Lazzaroni, the Italian word for beggars. The Lazzaroni failed in their
attempts to obtain federal funding to develop a national astronomical observatory, but they were
successful in influencing the staffing and operation of the U.S. Naval Observatory, including the
hiring of Simon Newcomb and the construction of a world class refractor telescope. Still, the
question remained, lacking national support, how were American astronomers ever going to be
able to compete with the Astronomers Royal of Europe?
While they were not aware of it, a peculiar turn of events would soon offer the Americans
a rare opportunity to best their European colleagues. For more than a century European
astronomers had been struggling to overcome a major hurdle. Their most careful observations,
made with the best instruments they could build, were simply not repeatable to better than
several tenths of a second of arc. Sir George Biddle Airy, the Astronomer Royal of England,
worked feverishly to find and solve the problem. He even invented a radically new instrument, called a
Reflex Zenith Tube (RZT) that incorporated a pool of mercury as an optical element, to
eliminate the effects of temperature changes, gravitational loading, and uncorrected atmospheric
refraction. In 1882, after thirty years of continuous work on the RZT, the instrument was
abandoned as a hopeless failure, and Airy was no closer to the source of the scatter in the
Greenwich observations.
A few years later, in 1884, Seth Carlo Chandler, Jr., began a series of observations with
his newly designed "Almucantar." Chandler's instrument also contained a pool of mercury, not
as an optical element, but as a flotation bearing which kept it accurately pointed at a constant angle
above the horizon. Within months, Chandler detected a systematic variation in the latitude of
Harvard College Observatory. In 1891, Chandler announced his discovery of variation of
latitude. Imagine the reactions of the Astronomers Royal when they learned that Chandler's
discovery was based on observations that he had collected with an instrument of his own design,
which cost less than seven hundred dollars to build, and, that he was not a professional
astronomer at all, but an actuary. To make the whole affair more difficult for the Europeans,
another American, Simon Newcomb, immediately reconciled the long standing, but flawed
theory, with Chandler's remarkable findings. Chandler and Newcomb proved that American
scientists could compete with European scientists, a critical step toward the federal government
providing funds to support national research programs.
|
WIN a FREE book!