Frémont's
Meteorological
Contributions
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says 284 websites link to this page.
Copyright ©2001 by Bob
Graham
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The elevated and arid plains of North
America, similar to the steppes, has
become known only since the surveys of
Frémont at the time of his first
completion of the circuit which defined it
and proved its existence.
Lorin Blodget,
Climatology of the United States and
the Temperate Latitudes of the North
American Continent, 1857.
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 At
the age of 24, Frémont applied for, and was
appointed, a civil engineer in the newly organized
Army Topographical Corps of Engineers by President
Jackson. A number of government and railroad
surveys followed. In 1838 Frémont was
commissioned as Second Lieutenant of Topographical
Engineers, and was assigned as chief assistant to a
survey of the area between the upper Missouri and
Mississippi Rivers.
 Leading
the expedition was fifty-two year old Legend of
Honor member Joseph Nicolas Nicollet, an eminent
French astronomer and mathematician, and foremost
surveyor and mapmaker of his day. Nicollet, had
been the protoge of Laplace, and is recognized in
the last vol. of Mecanique Celeste as an observer
of comets, and for his work on the great map of
France. At the time of the revolution of 1830,
Nicollet was astronomer at the Bureau of Longitudes
at the Royal Observatory in Paris. Financially
ruined by the revolution, he came to America, where
he became associated with Rudolf Hassler of the U.
S. Coast Survey.
 This
was a stroke of luck! With Frémont's
background in mathematics, astronomy, and the
physical sciences, Nicollet trained him in
surveying, botanical, meteorological, and
geological observation, and topographical map
work.
In 1839, J. R. Poinsett, then Secretary of the
Department of War, requested of Nicollet that he
write an essay on Meteorological Observations. The
essay was published by the Corps of Topographical
Engineers. It is primarily a collection of
questions and suggestions of topics to be
studied.
If Nicollet's 1839 Essay on Meteorological
Observations is considered seminal,
Frémont's 1848 Geographical Memoir Upon
Upper California, which accompanied the government
publication of the 1848 Frémont/Preuss map
of Upper California and Oregon, must be, in some
regard, not just seminal, or contributory, or
pioneering, but definitive.
On pp 6-7 of the 1848 Geographical Memoir is an
entirely current description on the meteorological
dynamics of the western states.
"It [Sierra Nevada] is a
grand feature of California, and a dominating
one, and must be well understood before the
structure of the country and the character of
its different divisions can be
comprehended.
"It divides California [here pre
state boundary, which includes the Great
Basin] into two parts, and excercises a
decided influence on the climate, soil, and the
productions of each.
"Stretching along the coast, and at a
general distance of 150 miles from it [here
again, the large picture], this great
mountain wall receives the warm winds, charged
with vapor, which sweep across the Pacific
ocean, precipitates their accumulated moisture
in fertilizing rains and snows upon its western
flank, and leaves cold and dry winds to passage
on to the east. [an orographic effect--a
Rainshadow]
"Hence the characteristic differences of
the two regions [today's state of California
and the Great Basin]--mildness, fertility,
and a superb vegetable kingdom on one side,
comparative barrenness and cold on the
other."
The next paragraph reports on illustrative
thermometric observations, and descriptions of
seasonal growth of grass, flowers, &c, and ends
with,
"Thus December, on one side of the
mountain, was winter, and on the other side it
was spring."
Frémont's report of his winter crossing
of the Sierra in 1844 provides an interesting
historical account of weather conditions, both from
his descriptions, and from his hypsometrical
determinations. For instance, when his last
barometer was broken in 1844, he used boiling point
observations (graduated to 1/5°f grad)
--assumed emersion of the thermometer in snow
water, as the Hypsometer was not invented until
1846; but his instrument would have been calibrated
in same manner.
On February 20, 1844, at the top of Carson Pass,
he recorded a boiling point of 197.5°f.
Converting his observed temp to "Hg, and because I
know the actual camp elevation where the
observation was made, I can reduce it to sea level
(30.305'Hg). The further reduction of his
observation puts his elevation at 8600', which is
nearly on-the-money for the summit of Carson
Pass.
Nice Sierra winter weather--a good strong high
pressure ridge just sitting there. And because this
continued over the next three weeks in 1844, it
saved the expedition from disaster.
Handy formulas to determine elevation by
barometer or boiling point and to reduce upper
level barometric readings to mean sea level
equivalent.
You can also download an Excell spreadsheet to
do this for you.
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Wonders
of modern science
department!
We can now see these things happening.
This radar image is from an early winter
storm December 1, 2001. The section is
through the State of California between
San Francisco and Lake Tahoe. It shows
rain in the valley, changing to mixed rain
and snow in the mountains at about 4000',
and snow between 5000' and 10,000'. Notice
that no precipitation is falling beyond
the Sierra Nevada.
Click the image
for current conditions
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 This
was Gold Medal material! This complete
understanding, based on observation and
data collection, is enough to have
established Frémont's reputation as
a Scientist of the first order.
(at right, the Gold Medal
personally presented to Frémont by
Baron von Humboldt for his contributions
to geogrphy and science)
I can think of few other examples in
American literature of such original clear
scientific reasoning, based on
observation, leading to such a remarkably
correct conclusion--indeed, in four
sentences, a complete system. Thoreau's
THE
SUCCESSION OF FOREST TREES, an
address read to the Middlesex Agricultural
Society in Concord, Massachusetts
September, 1860 would be another.
As here referenced: "Every one has heard
that when an American Forest is cut down,
a very different vegetation springs up."
Charles Darwin, On the
Origin of Species, firth edition,
1869
Frémont was the first to
scientifically examine and map (and coin
the name of) the Great Basin. It is to be
remembered that there were then no
political boundarys; all being Mexican
territory, "California" extended from the
Pacific to the Rocky Mountains and north
to the line of the present Oregon
border.
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Directly related to
Meteorology:
The First measurement of the altitude
of a high peak (14,000') in North America.
My views on the route and the peak
conquered by Frémont in the Rocky
Mountains in 1842.
A history of Frémont 's training
in mathematics, navigation, and
mapmaking.
Includes the barometric readings
taken on the ascent.
And a record of possible climatic
changes since 1842.
The method of determining elevations by
thermometric observations on part of
Frémont's 2nd
Expedition--Hypsometry.
The mountain barometer.
And:
Frémont's methods of determining
coordinates.
Frémont's contributions to
BOTANY.
and GEOLOGY
Or,
to see a study of the determination of
latitudes by Francis Drake, and how the
errors in those determinations point to
the actual location of his 1579 California
landfall.
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A brief bibliography:
Blodget, Lorin,
Climatology of the United States and
the Temperate Latitudes of the North
American Continent, J. B. Lippincott
and Co., Philadelphia: 1857.
Frémont, Brevet
Captain J. C., Report of The Exploring
Expedition to the Rocky Mountains in the
Year 1842, and to Oregon and North
California in the Years 1843-'44,
Printed by order of the Senate of the
United States, Gales and Seaton,
Washington. 1845.
Frémont, John
Charles, Geographical Memoir Upon Upper
California, Senate. 30th Congress,
Misc. No.148, Wendell and Van Benthuysen,
Washington, 1848.
Greely, Gen. A. W.,
American Weather, Dodd, Mead &
Company, New York, 1888.
Goetzmann,William H.,
Army Exploration in the Americn West
1803-1863, Yale University Press, New
Haven, 1959.
Negretti & Zambra,
A Treatise on Meteorological
Instruments, London, 1864.
Nicollet, J. N.,
Essay on Meteorological
Observations, Printed by order of the
War Department, Washington,
1839.
Smithsonian
Meteorological Tables [Based on
Guyot's Meteorological and Physical
Tables] Second Edition (1893) -
Smithsonian Miscellaneous Collections -
1032.
Williamson, R. S.,
On the Use of the Barometer on Surveys
and Reconnaissances; part I,
Meteorology in its Connection with
Hypsometry; part II, Barometric
Hypsometry; D. Van Nostrand, New York,
1868.
interest, comments, or
questions
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