Global Positioning System Reference
In-Depth Information
cal, but in the opposite sense: he thought that the earth was squashed at the
poles (fig. 2.8b). The eminent Dutch physicist Christiaan Huygens agreed
with Newton, and thus, the battle lines were drawn. 12 The Cassinis insisted
on an earth stretched at the poles, based on their observations, whereas
Newton and Huygens believed in a squashed earth, based on Newton's
theory. Who was right?
Doubts about the validity of the Paris data grew within the French camp,
and two expeditions were sent across the world in 1735 and 1736 to settle
the matter. One expedition, headed by Charles Marie de la Condamine and
Pierre Bouguer, traveled to Peru to measure the length of a 1\ meridian arc
near the equator. 13 A second expedition under Pierre-Louis Moreau de
Maupertuis conducted a survey in Lapland to determine the length of a 1\
arc near the North Pole. The surveys were conducted with unprecedented
accuracy, and the result was unequivocal: the earth was flattened at the
poles, as Newton and Huygens (and several French surveyors, including
Maupertuis) had thought. The eminent French philosopher Voltaire got
involved in the acrimonious aftermath of these expeditions, saying to Mau-
pertuis, ''You have flattened the earth and the Cassinis.'' He said to a
member of the other expedition, ''You have found by prolonged toil what
Newton had found without even leaving his home.'' 14
The expedition results may have been painful to the Cassinis, but the
important point to note is that science was being conducted properly.
Experimental evidence determines the facts; theories are good, but only if
supported by observation; bad data are acknowledged and fixed. Egos may
influence the discussion (scientists are people, after all) but not the pro-
cess. Here we have an early example of modern scientific method, right
down to the large cost of the expeditions.
12. Cassini and Huygens were both honored in 1997 with the launch of the NASA/Euro-
pean Space Agency Cassini-Huygens satellite mission to Saturn.
13. The site is in modern Ecuador, which did not then exist as an independent nation.
Indeed, when Ecuador obtained its independence in 1830, its name was chosen, so it is
claimed, in part because of the prestige bestowed on it by the French geodetic mission to its
capital, Quito, almost a century earlier.
14. The quotes are from Smith (1997). To read further on the Picard and Cassini surveys,
and on the controversy about the shape of the earth (which displayed a great deal of ego,
animosity, petulance, intrigue, ambition, and professional rivalry, as well as extraordinary
e√ort, determination, and immaculate surveying techniques), see Danson (2006), Jardine
(1999, chap. 6), Konvitz (1987), Murdin (2008), Terrall (2002), and Whitaker (2004, chap.
7). Long after the French expeditions, it was shown that there were errors in their calcula-
tions that exaggerated the flattening e√ect.
 
Search WWH ::




Custom Search