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BOOK REVIEW

“The Measure of All Things:

The Seven-year Odyssey and Hidden Error
That Transformed the World”

Written by Ken Alder
Reviewed by J. J. Waller Jr., MD

It is 1892, in the midst ically measured line distance between the two angles, thereby de-
of the French Revolution. termining the third angle of the triangle, and by geometry the abil-
The French Academy of ity to determine the length of the other two sides. The reference
Sciences (existing since points or stations would be set up several miles apart along the
the 17th century) has de- longitude and this would allow multiple triangles to be determined
termined that a new sys- since the sides of one of the triangles would be known and thereby
tem of measurements has become necessary. This fascinating story the other sides of the progressive triangles could be determined.
is told in Ken Alder’s book, “The Measure of All Things: The The stations or measuring points would be mountaintops, tops of
Seven-year Odyssey and Hidden Error That Transformed the steeples of churches, the tops of taller buildings or, if necessary, the
World.” construction of scaffolding reaching several hundred feet in the air
At the time, there were multiple systems of measurement to mark a determining station. In this way, the entire distance be-
throughout the world. Not only did each country have its own tween Dunkirk and Barcelona could be accurately determined. In
system of weights and measures, but generally each state within a this way, only the original base triangle at each end needed one
country also had different types of measurements. For example, side to be accurately measured, and this would be done on a flat
France had 260 standards producing various results, so the actual level along a road several miles in length and measured accurately
value of a bushel or a barrel could vary among areas. The same with a ruler to determine the exact length.
held true internationally, making uniform commerce and trade al- Multiple sighting stations or points along the route would be
most impossible and, at the least, extremely complicated. utilized, but unfortunately not all of the area was flat, and many
It was decided by a number of savants in various countries that of the observation points along the way were in mountain passes
there should be a uniform standard for weights to be calibrated in or in steep mountain ranges such as the Pyrenees in southern
grams and lengths to be determined in meters. A decimal system France. Variants in climatic conditions were a hindrance and
was definitely indicated. It also was decided that the length of the made telescopic observations and sightings nearly impossible,
meter would be 1/10,000,000 of the distance along a meridian of causing delays of weeks or months until the weather permitted
longitude between the North Pole and the equator, which would better observations.
equal actually 90 degrees of latitude. Delambre was assigned to measure the northern half of the
distance and Mechain was assigned the southern half. This way
ASTRONOMERS ASSIGNED they would meet in the middle (somewhere south of Paris), and
Two men, both accomplished French astronomers, Jean De- then the entire information accumulated and the distance de-
lambre and Pierre Mechain, were assigned the task of measuring termined. The original estimation of the time required for this
the distance along the longitude from Dunkirk in northern task to be performed was one year. Work started in 1892, and
France to Barcelona, Spain, running on the longitude through after multiple delays and complications, it was completed within
Paris. The two end points were slightly over 10 degrees of lat- seven years, in 1899.
itude apart and were at sea level. From this distance, the meas- The two astronomers were entirely different in their tempera-
urement from the pole to the equator would be extrapolated and ments. Both were extremely intelligent but Delambre was more
the meter length determined. relaxed, pleasingly aggressive, cooperative, and kind to his associ-
The distance from Dunkirk to Barcelona would be determined ates. He had several scientists assisting him, as did Mechain, and
by means of geodesic use of triangulation. A base triangle at each he shared easily the observational methods with his assistants, shar-
end would be determined with two measured angles and a specif- ing his log work and his mathematical calculations as they assem-

38 San Antonio Medicine • February 2014