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Wind River Range
Identification of the peak Frémont climbed in 1842
Copyright © 1999, 2001 by Bob Graham

I have not been to the Wind River Range. But from following the narrative of the Report of the 1st Expedition, the examination of the Preuss map and USGS DEM files of topographic quadrangles, and the barometric register of Frémont's observations, I have come up with the route that I think best fits the description of the account in the Report of the 1842 expedition. The route leads to the peak Frémont called "Snow Mountain" that modern maps call Fremont Peak.

Many historians and biographers have characterized Frémont's 1842 climb of the peak in the Wind River chain as not only reckless and ill advised, but vainglorious. In actuality, it was probably the most important scientific work performed on the expedition. No high peak had ever been measured in North America, and geographers had no real knowledge of the height of the storied Rocky Mountains. This was pioneering use of barometry in exploration--first introduced into survey work by Frémont's mentor Joseph N. Nicollet. The barometric observations made were not only a first, but a very thorough and as useful today as when they were made in 1842.

In making an identification of the 1842 expeditionary route, and identity of the particular peak climbed, all of the following have been examined:
Fremont's narrative, as published in the 1843 Report to Senate of the United States.
Frémont's Tables of Astronomical Observations, and Meteorological and Barometric Registers--appendices to that report.
The Report illustrations, drawn by Charles Preuss.
The 1843 Frémont / Preuss map.
Expedition cartographer Charles Preuss's diary.
See bibliography below.

The Report Illustrations

These are the two engravings of the drawings made by Charles Preuss in the Wind River Chain of the Rocky Mountains in 1842. The first is from the approach (at Lost Lake), with Frémont and Jackson Peaks to the right. The second is of Island Lake with Frémont and Jackson Peaks behind it on the left. The base camp is atop the foaming torrent, which tumbled into the little lake about one hundred and fifty feet below us.

go An aerial map of the approach route.

More than one critic has objected to these drawings as whimsy--not representing the actual landscape. There is no question that Preuss has somewhat exaggerated the vertical in his renderings, but there is nice correspondence when considered as a whole.

go See how these two views combined represent the range, and also the approach route from Two Buttes and Boulder Lake.

Frémont recorded on page 67 in the 1843 Report that the range...is correctly represented in the view from the camp of Island Lake--the lower image here, which is the frontispiece. In the 1845 Report it is p.70 and facing.

The above view of Island Lake is looking approximately east at Fremont and Jackson Peaks, whereas this postcard image is looking north, up Titcomb Valley, with Mt. Woodrow Wilson off in the distance.

Other Preuss location drawings and correlations:
go Long Camp at Carson Pass
go Pyramid Lake, Nevada

The Report Narrative of the Climbing Routes

There are two climbing routes described in the narrative; two days, and two different attempts.
Based on the narrative entries from the Report, and these visual correlation's, the image to the right depicts my tentative view of the two routes that were taken--the failed attempt of the 14th of August, 1842, and the successful attempt the following day. These are only approximate climbing routes.

On the August 14th, Frémont recorded, On every side as we advanced was heard the roar of waters, and a torrent, which we followed up a short distance, until it expanded into a lake about one mile in length. This would be the lakes in Titcomb Valley--they combine to this length--no other lake or combination does. They, immediately have to contend with ice fields: On the northern side of the lake was a bank of ice, or rather snow covered with a crust of ice.

On August 15th, by an entirely different route, to the left of yesterday's route, he recorded passing three small lakes of a green color, each perhaps a thousand yards in diameter. This time, instead of the roar of waters...a torrent, they follow a small stream. Preuss adds in his diary, toward the base of the next highest peak, which I take to be Jackson Peak, the route through Indian Basin. They do not encounter snow until about 1800 feet above the lakes. The summit itself was bare rock, (sienitic gneiss), but on the back side of the peak, the shaded side, he discovered a massive field of ice and snow--this is today called Frémont Glacier.

go Frémont Peak is a popular climbing venue. Most climbers have no idea they are reenacting what was a front-page event in 1842. This link is to one climber's (Martin Cuma) photographic record of the climb. This takes a bit of time to load, but when fully loaded, clicking in various places along the red climbing route brings up photographs of the vantage from that particular point.

go Here is another which shows climber Jeremy Hanks atop the peak. Frémont wrote, "I sprang upon the summit, and another step would have precipitated me into an immense snow-field five hundred feet below." Jememy is shown not springing onto the summit, but "clinging" to it--"I don't use the term 'clinging' lightly either. The wind was gusting over 40 MPH, and there was a sheer cliff just below me!"

A Summary of Expedition Movements between August 14 and 16, 1842

8/14 Having had no food since the previous mid day, Frémont sets out from the Island Lake camp, and proceeds up Titcomb Valley. They make the first attempt on Fremont Peak.

Preuss and Carson get within 1000' of the summit, but cannot proceed.
Frémont becomes ill, and directs Basil Lajeunesse to return to the Mule Camp (*Lost Lake) and, if possible, to return with mules and blankets and food. Later, having recovered, Frémont returns to the Island Lake camp, and, a short time later, Basil returned with animals and supplies.

8/15 In the morning, with all rested and fed, Carson returns to the Mule Camp with all except Preuss, Lajeunesse, Lambert, Jannisse, and Descoteaux [de Couteau]. Mounted on mules, Frémont leads them up through Indian Basin to the base of Jackson Peak. From there they proceed to the Summit of Fremont Peak.

They take barometric readings and compass bearings, and return in the afternoon to the Island Lake camp.

8/16 In the morning they leave Island Lake, find the burnt out fires of the Mule Camp and supplies that have been left behind for them, and proceed on to the main camp at Boulder Lake.

* The approach route August 10-13. go


Never before had anyone attempted to measure the Altitude of an American mountain with a barometer.
William H. Goetzmann, Army Exploration of the American West

The Barometric Observations

Frémont says that the peak climbed was 13,570'-- determined by reduction of the barometric observations made on the summit and at the camp at Island lake. The reductions are not shown in the appended tables; however, they were based on comparison with the barometric register of Dr. Engelman at his observatory in St. Louis. St. Louis is over 1000 air-line miles east of Frémont's observations--much too removed, but the only data then available.

So, I ran Frémont's Wind River barometric observations from the 1843 Report (page 195) through my HP67 calculator in a program I devised several years ago using the formula:

Z= 62,900 log10 P0/P, where Z=altitude in feet, P=Pressure at the upper limit in any units, and P0=pressure in same units as above corresponding to zero altitude.
This is an old Bureau of Standards formula once used in calibrating aircraft altimeters. It works well to 15,000' at middle latitudes, and assumes a mean temperature of the air column (isothermal temperature) of 50°f.
go Click for the program for use in HP programmable RPN calculators.
And () as a download in an Excel® spreadsheet.

Below are my reductions (not Frémont's) using Frémont's barometric readings as published in the Report.

By the USGS map, Island Lake is 10,346'.
The campsite is stated in the narrative to have been at the top of the waterfall, 100 feet above the level of the lake, which, would be at about 10,446' elevation, and is shown on the aerial photograph at right. On a topographical map, this place is very close to the 10,440' contour. (Note--John Grebenkemper has since (2003) verified this elevation using WAAS enabled GPS.)

The elevation of the Island Lake campsite, as the one known, is used as a constant in all the following calculations.
The sea level equivalent pressure for the that camp is then calculated for each day to match Frémont's barometric observation. Like Standard Time, as opposed to Local Time, this is a now standard mathematical reduction: it is how your weather station, or home barometer, presents the data.
The resulting sea level equivalent is then used in making determinations for the other observations on the same day at the unknown elevations.

"Com'on, Bob; do you really place any confidence in Frémont's jury-rigged barometer?"

Yep. Absolutely. A mercury barometer is a direct-reading instrument. The repair as described should have had no effect on the accuracy of the instrument. Indeed, this has since been verified by John Grebenkemper in his 2003 analysis of Fremont's barometric register during these days. On site, in June 2004, John also confirmed the elevation of the campsite with WAAS enabled GPS.



sea level


8/13, 5:30 pm

Island Lake camp (10,466')



10,446' el.

8/13, Sunset

Island Lake camp (10,466')



10,446' el.

8/14, Sunrise

Island Lake camp (10,466')



10,446' el.

8/14, noon

Gap reached by Preuss



12,043' el.

8/14, 5:00 pm

Island Lake camp (10,466')



10,446' el.

8/14, Sunset

Island Lake camp (10,466')



10,446' el.

8/15, Sunrise

Island Lake camp (10,466')



10,446' el.

8/15, 6:00 am

Island Lake camp (10,466')



10,446' el.

8/15, 9:30 am

Indian Basin



10,722' el.

8/15, 1:00 pm

Summit #1



13,727' el.

Summit #2



13,767' el.

8/15, Sunset

Island Lake camp (10,466')



10,446' el.

8/16, Sunrise

Island Lake camp (10,466')



10,446' el.

The results are interesting, as it is a near fit to the proposed route, but to no other.
Note the variation of the pressure at the Island Lake camp: Frémont records a wind storm on the 13th followed by fair weather.
The results look very close to Frémont Peak's elevation of 13,745'; Mt. Woodrow Wilson is 13,502'.

Why is the Report elevation given as 13,570'--lower by 175' than today's surveyed elevation of 13,745'?

The elevation reported in the narrative portion of the 1843 report gives the elevation of the peak as 13,570".
The reduction of the barometric observations taken on the mountain were done by Dr. George Engelmann at the government observatory in St. Louis after the return of the expedition. Dr. Engelmann's barometric register covering the period of the expedition was publised as an appendix to Frémont's Report, and was apparently used in the reductions of Frémont's observations. Though too far removed from Frémont's locations, there was then no collected barometric data west of St. Louis for reduction purposes. The report states only that in calculation, the tables used were those of Bessel and of Oltmanns, as given in Humboldt. They did the best they could, and it wasn't bad for pioneering work on a reconnaissance.
Dr. Engelmann was a founder of the St. Louis Academy of Science and the Missouri Botanical Garden--the latter a repository for many botanical specimens collected on Frémont's expeditions. In 1998 the Missouri Botanical Garden published Stanley Welsh's John Charles Frémont Botanical Explorer.
go About Frémont's botanical contributions

Map and Engelmann street address courtesy of Andrew Colligan, Archivist, Missouri Botanical Garden

Additional useful infirmation was kindly sent by Cal Stuart at the Missouri Historical Society.

Most of the hypsometrical measurements...made by different explorers during the last twenty years or more, by Nicollet, Frémont, Owen, Wisliznus, Emory, Stansbury...took the altitude of St. Louis as their starting point, and were based to a great extent on the barometrical observations of those explorers compared with mine. George Engelmann, 1859

Frémont's barometers had been calibrated at the observatory in St. Louis before he left. If they had survived the expedition, they would have been compared again on their return. But Frémont's barometers never did make it back.

August 16, 1842. In the course of the afternoon's march the barometer was broken past remedy. I regretted it, as I was desirous to compare it again with Dr. Englmans barometers at St. Louis, to which mine were referred; but it had done its part well, and my objects were mainly fulfilled It had touched the highest point of its destiny, and would never be put to a less noble use.

go Mercurial barometers are fragile.
go Read the report of an early use of the aneroid barometer on a survey

OK; Frémont Peak is not the tallest peak in the Rocky Mountains. What Frémont said was this:

The height of these mountains, considered by the hunters and traders to highest in the whole range, had been a theme of constant discussion among them; and all had looked forward with pleasure to the moment when the instrument, which they believed to be true as the sun, should stand upon the summit and decide their disputes.....From the description given by Mackenzie of the mountains where he crossed them, with that of a French officer still farther to the north, with Colonel Long's measurements to the south, joined to the opinion of the oldest traders of the country, it is presumed [my emphasis] that this is the highest peak of the Rocky Mountains.

go How this all works--Hypsometry.

BUT, what is astonishing, is that Frémont did this after having repaired (major structural repairs!) to his barometer a few days before. He had a perfect conceptual understanding of the instrument--no doubt part of his training under Nicollet.
And a good measure of what was once called Yankee Ingenuity. Imagine! Getting these readings with a barometer with a cow horn cistern stuck on with camp-made hide glue.
go The barometer repair.

The G. P. A. Healy portrait

The little seen portrait at left by G. P. A. Healy (1813-1894) is in the collection of the Union League Club of Chicago. It shows Frémont in front of a portion of the view of the Wind River Range drawn by Charles Preuss (cf. top image above). Frémont is represented here as a man of about the 28 years of age that he was in 1842. It is not known, however, exactly when this portrait was painted, or if it was done from life.
The Wind River view used by Healy is the version of the Preuss drawing not published until 1845, by which time Frémont had received a double Brevet to Captain, so the earlier rank depicted is probably to commemorate the feat. It is one of only two portraits that I know of showing Frémont in the uniform of a second lieutenant. The other is shown at right. It appears in James M. Cutts' The Conquest of California and New Mexico, 1847. It is possible that this, an engraving that may have been done from a daguerreotype (and therefore reversed, or reversed again by the engraver) was used as the model for the Healy painting.

go See some of the published peak illustrations 1856-1900.


go Frémont's contributions to METEOROLOGY; seminal work, but a Definitive result.

go Fremont Peak, 1842. "The summit rock was gneiss, succeeded by sienitic gneiss. Sienite and feldspar succeeded in out descent to the snow line, where we found feldspathic granite." Frémont's contributions to the then emerging science of modern GEOLOGY.

go Geomorphologist and Paleoclimateologist Scott Stine uses his knowledge of the Great Basin and Sierra Nevada to plot the 1833 trail of Joe Walker--Revolutionary!

go Frémont and Charles Preuss climb Red Lake Peak in the Sierra Nevada on February 14, 1844 to look for the Sacramento Valley and discover Lake Tahoe.

go Everything changes; even polaris has moved half a degree closer to the celestial pole since 1842.

August 7th, 1878, Summit of Frémont Peak
We found no signs of anyone having visited this point before; but I am of the opinion that this is the point reached by Frémont in 1842.
A. D. Wilson of the Hayden Survey.

go Three other viewpoints on the Wind River climb: A. D. Wilson, Bonney and Bonney, David Roberts, are found on this introductory page.


Blodget, Lorin, Climatology of the United States and the Temperate Latitudes of the North American Continent, J. B. Lippincott and Co., Philadelphia: 1857.

Bowditch, Nathaniel, Ll. D., The New American Practical Navigator, E. and G. W. Blunt, New York, 23rd Edition, 1853 (includes year 1842).

Frémont, J.C., Lieutenant, A Report on an Exploration of the Country Lying Between the Missouri River and the Rocky Mountains, on the Line of the Kansas and Great Platte Rivers, Senate Document 243, Washington, 1843. Contains the 1843 Frémont/Preuss map.

Greely, Gen. A. W., American Weather, Dodd, Mead & Company, New York, 1888.

Middleton, W. E. Knowles, A History of the Barometer, The Johns Hopkins Press, Baltimore, 1964.

Negretti & Zambra, A Treatise on Meteorological Instruments, London, 1864.

Nicollet, Joseph Nicolas, Essay on Meteorological Observations, Printed by order of the War Department, Washington, 1839.

Nicollet, Joseph, eds. Bray, Martha Coleman, The Journals of Joseph N. Nicollet, Minnesota Historical Society, St. Paul, 1970.

Plympton, George W., The Aneroid Barometer; Its Construction and Use, D. Van Nostrand Company, New York, 1884.

Preuss, Charles, Exploring With Frémont, Translated by Erwin G. and Elisabeth K., Gudde, University of Oklahoma Press, Norman, 1958.

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; New York, D. Van Nostrand, 1868.


©1999, 2007
Bob Graham