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Maps

Always the man of vision, ever living life as a learning experience, and in all ways attending to the details, Thomas Jefferson sought to prepare the Lewis and Clark Expedition with as complete a cartographical and geographical picture of western lands as possible (1). Jefferson had his own collection of maps, just as he had his own very substantial library, which he and Meriwether Lewis used to prepare Lewis for the path through poorly charted Louisiana Purchase lands (2).

There was another student of maps among them, and that was Albert Gallatin (1,2). Gallatin had emigrated from his birth home in Switzerland to Western Pennsylvania. He was already a public voice in the Pittsburgh area by the time of the Whiskey Rebellion in 1794, and is credited with helping to moderate the climate of that conflict. He was a Republican minority leader in Congress during the Federalist domination, before the election of Jefferson to the Presidency. Once in office, Jefferson appointed him Secretary of the Treasury, and he served in government thereafter in various capacities (3). He also was knowledgeable about the Indian tribes of the west, and his writings have been referenced (4). A product of his work with Jefferson and Lewis was a "Nicholas King map" that charted the territory from the Mississippi River to the Pacific Coast, as best as it could be known just before embarking to the west (1). Gallatin was helping to assemble a composite from different sources, although Cutright allows that it is only conjecture whether or not that was completed.

Mapmaking was in itself an ongoing enterprise because of the paucity of information at the turn of the nineteenth century. Elliott Coues in Vol. II (4) has a foldout tracing of the map sent back by Lewis to Jefferson from Fort Mandan, April 7, 1805. The Corps was yet to enter the least well charted lands of the Louisiana Purchase. A topographical foldout from William Clark, 1814, done well after completion of the Expedition, is in the same volume for comparison. In Vol. I is a "modern" map obtained by Elliott Coues in his time from the U.S. Geological Survey (4,5). It can be a real treat for the interested reader to pore over these fine examples of cartography in progress. Our mapmakers were incredibly good at what they did.

For those who prefer examining the maps electronically, there is an excellent Web site maintained by the Smithsonian Institution in Washington at www.edgate.com/lewisandclark/. Four maps are imaged at this site from the period or not long after. One is a Nicholas King composite map of 1803, apparently the one to which Gallatin contributed. Another is the Clark rendition of 1814. The reader has the capability to zoom in and out while inspecting these wonderful treasures from the Lewis and Clark Expedition of 1803 - 1806. They illustrate in just one more way how well planned and scientific this historical voyage was.

They also help us to realize just how difficult the route of the Expedition was, not only because of obviously tough mountain topography, but because of the latitudinal course of the Ohio and Missouri Rivers as well. The Expedition took the Corps into the cold of a North Dakota winter in 1804-1805 at Fort Mandan. The latitude of Fort Mandan, not far from today's Bismarck, is nearly 47° N. Toronto, Canada, falls well south of this between 43° 30' N and 44° N, and Pittsburgh, at the headwater of the Ohio, lies near 40° 30' N. There is a point to be made about the inevitable seasons in North America, which can be followed with the help of the figure below.

The figure shows the earth at the winter solstice on the left and at the summer solstice on the right, if you imagine the sun in between and radiating its parallel rays (orange) of electromagnetic energy to earth, here shown equidistant from one another. The approximate position of Pittsburgh is denoted by the small star, in each case coincident with an arrowhead. For each earth picture, a light blue half is in full sun exposure, and a shaded half is in darkness. Pittsburgh's position is shown at noon, on the dark circular border facing the direction of incoming rays. There is an excellent Web site that shows the 3-D spatial situation in animation; it is at http://vortex.plymouth.edu/sun/sun1.html .

There are two reasons why summer is summer in Pittsburgh, and winter is winter. One is that line segment "b" is greater than line segment "a." These are Pittsburgh's paths of travel during earth's rotation about its imaginary axis at each solstice. In the summer Pittsburgh's days are simply longer, longest at the summer solstice and shortest at the winter solstice, and that is the meaning of b>a. The second has to do with the sun's energy/arc length of earth. Notice by the length of arc between equidistant rays that this ratio must be less for Pittsburgh in the winter than in the summer. The arc length of the denominator between rays is greater in the winter, while the sun's energy is relatively constant, which results in a lower energy density.

From the figure, you can even see that it is nighttime all day long at the North Pole around the time of the winter solstice, and daylight all day during the summer solstice. Even in the pole summer, the sun's energy density is low. Fort Mandan's latitude lies between Pittsburgh and this extreme, so cold it is during a usual winter season. Pittsburgh too, obviously, also has a seasonal winter, although generally of lesser severity. It should be mentioned that the extremes of summer and winter tend to lag the solstices, as the earth's surface needs some time to warm up or cool down.

Inquiry project: Do an analysis for why Mars has seasons?

The reality of planning the Expedition was that the Corps needed to make its way in the favorable seasons, but plan as well for settling in during the winter months. Lewis and Clark did winter over three times after departing from Pittsburgh, first near St. Louis, then at Fort Mandan, and then at Fort Clatsop (4), where the Columbia River finally drains into the Pacific Ocean. They could not continue to travel in winter as we freely do for the most part, but their time in place was not really wasted. In part, it was a time for Lewis and Clark to assimilate local information about the course ahead, and to be more reflective on all matters, especially the cartography of the route to come. This period of taking stock at milestone points is integral to all good science.

Inquiry project: Determine how NASA scientists and engineers work at assimilating data and at what intervals.


Map References

1. Cutright, Paul Russell, Lewis & Clark: Pioneering Naturalists, Lincoln, NB: University of
    Nebraska Press (1989), pp. 4, 37-40.

2. Ambrose, Stephen E., Undaunted Courage, New York: Simon & Schuster (1996), pp. 80, 91-92.

3. Morison, Samuel Eliot, The Oxford History of the American People, New York: Oxford University     Press (1965), pp. 341, 353, 361.

4. Coues, Elliott, ed., The History of the Lewis and Clark Expedition, Vol. I - III, New York: Dover     Publications (1987 reprint of Francis P. Harper's unabridged 1893 edition).

5. Cutright, Paul Russell and Brodhead, Michael J., Elliott Coues: Naturalist and Frontier Historian,     Urbana and Chicago, IL: University of Illinois Press (1981), p. 348.

 


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