Page 39 - Layout 1

BOOK REVIEW

bled the data. Mechain was entirely different and was was always hesitant to share his data. He had sent
a maniac for precision. He refused to allow anybody some early data about his calculations of the latitude
but himself to make angular measurements. He kept of Barcelona but later, upon leaving Barcelona, he dis-
all the log records himself, performed all the mathemat- covered a miniscule error in his measurements. After
ical calculations, and trusted no one but himself on his trying repeatedly to get back into Spain to repeat his
particular half of the mission. This caused great delays measurements, he was never allowed to return and he
in the performance of his job. nearly went mad with the thoughts that he might be
accused of inaccuracy by the Academy and be in dis-
REPEATING CIRCLE grace. He became more paranoid and made triangular
The angle measurements were made with an instru- measurements over and over again, delaying his com-
ment known as the “repeating circle.” Made by the pletion of the southern portion of the mission. He
most accomplished instrument-maker in France, Jean refused to send further data to Delambre.
Borda, the circle is made of two extremely strong tele- They finally met at the midpoint of the mission
scopes mounted on shared circular metal axes to meas- after extreme persuasion by Delambre on his associ-
ure the angles between the two scopes. One mounted ate, with additional demands by the Academy and the
above the axis; the other below. The scopes could be French government (now under Napoleon). He
rotated 360 degrees to make multiple angle measure- agreed to return to Paris. The data from both men
ments of the two stations being measured. Seven to 10 were presented to an international assembly being
sightings were performed on each of the angles deter- held in Paris of savants from various countries to de-
mined for greater precision. The instrument could be termine the definite measure of the meter. The two
used with the axis on the horizontal to measure angles astronomers were welcomed as heroes. The commit-
on the Earth, or in the vertical to measure the angles be- tee, with the data obtained, determined the distance
tween stars and Earth to determine the exact latitude of between Dunkirk and Barcelona, extrapolated the dis-
a point. Exact latitude measurements had to be made at tance for the figure representing the distance from the
both Dunkirk and Barcelona to determine their exact North Pole to the equator, and then set the meter at
position on the longitudinal meridian. 1/10,000,000, which was equal to 443.44 ligna (a
The two savants encountered multiple obstacles on French measurement). Multiple meter lengths made
their mission. The French Revolution, being in full of platinum bars were produced for distribution to
swing, created a situation where every district through every country in the world. (Incidentally, only three
France had its own citizen militia ready to apprehend countries were not represented at this meeting. They
anyone appearing to be an aristocrat and trying to es- were Germany, England and the United States,
cape the country. Both groups were detained repeatedly, mainly for political reasons prominent at that time.)
sometimes for weeks or months at a time, until their Now international trade and commerce would be
true identity could be established. Their equipment was improved greatly with a uniform system of measure-
suspected of either being some source of magical evil ments based on the metric system. Delambre was re-
machine or a spying device for the country’s enemies. warded by being appointed the permanent secretary of
Prussia had declared war on France in an attempt to the Royal French Academy of Scientists, and Mechain
reestablish the monarchy, and then Spain also declared was made the permanent chief astronomer of the Na-
war on France. tional Observatory.
This occurred while Mechain was in Barcelona mak- Mechain died of malaria in 1804 while on another
ing measurements of the latitude. He was detained and geodetic survey in southern France. Delambre was ap-
kept in very courteous custody for a two year period, pointed the executor of all of Mechain’s scientific data
being allowed to travel freely around Barcelona, but un- (which he had saved in a trunk). After two years of in-
able to leave the country or have correspondence with tense review of Mechain’s data and logs about the mis-
France. Finally, peace was declared, and he was allowed sion, which were in a great distorted mess within the
to continue his meridian measurements going north. trunk, Delambre discovered the tiny initial latitude error
Periodically, progress notes and calculations were to made in Barcelona that would undoubtedly, to some de-
be exchanged between the two astronomers, and this gree, alter the true length of the meter. He faced a great
was done regularly by Delambre. However, Mechain continued on page 40
visit us at www.bcms.org 39