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Book Review Latitude: How American Astronomers Solved the Mystery of Variation by Bill Carter and Merri Sue Carter (Naval Institute Press, 2002). On a study break at the local library, I stumbled
across this book detailing the efforts of 19th century astronomers to
identify the variation in latitude. Leonard Euler had posited in the
1700's that the earth's axis should have a wobble (variation) with a
period of ten months, but one-hundred years of astronomical effort had
failed to confirm this hypothesis.
I found the book fascinating for several reasons. First, this is a solid story of American astronomers catapulting themselves to the forefront of the discipline. Second, Seth C. Chandler, whose work established the parameters of the variation, was an amateur astronomer in that he never went to college. Third, and most interesting, Chandler's first career was as an actuary in Boston. His 1872 paper in the Journal of the Institute of Actuaries is a modest prelude to his later, voluminous astronomical publications. Chandler's story is worth reading for the example of his accomplishments with a practical rather than college education, for the example of his painstaking observations and calculations, and for the example of his determination in reaching conclusions others ignored because they did not fit the accepted theory. The authors, a father and daughter team of astronomers, give a full sketch of the key astronomers of the time. I particularly appreciated the way in which the authors traced the line of relationships from teacher to student. Carl Friedrich Gauss (1777-1855) was eighteen when he discovered the method of least squares. In fact, earlier versions of the normal distribution have been referred to as the Gaussian distribution. Gauss, to return to the story at hand, oversaw the Ph.D. work of Benjamin Gould, an American who had gone to study astronomy in Germany. Gould, in turn, hired Chandler out of high school to work for him at the U.S. Coast Survey, doing calculations for the determination of longitude using telegraph signals. This was the practical education in mathematics, surveying, and instrument construction that would lay the foundation for Chandler's later measurements of variation. In our profession, we soon realize that
there is a great deal of data scrubbing to be done before even getting
to serious analysis. And we are all conscious of the need to anticipate
and defend against various clerical errors in the data (both the errors
made by others and those we make ourselves). Without belaboring the
comparison, I very much enjoyed the authors' moderately technical
discussion of the difficulties of various geodesic and astronomic
measurements. For example, in using telegraph signals to establish
longitude, equations and calculations were carefully constructed to
account and adjust for operator error. In leveling a telescope, the
spirit level is read forward, then read in the reverse position, such
that instrument errors can be divided out. When measuring present
values and insurance accounting flows, such examples of concrete
measurement errors and their corrections may be of some inspiration if
not practical assistance. In a similar vein, Chandler's construction of
several new astronomic instruments in his study of variation should
inspire us to grasp and rework the fundamentals of our own received
tools and methods.
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