January 3, 1804
On this day the Lewis and Clark journals recorded terrible weather at North Dakota’s Fort Mandan. Some experts raise questions about their thermometer. 
The reconstructed Fort Mandan in winter
“Verry Cold blustering day” wrote Captain William Clark, “the Merkery in Doneyan Co: Thermometer one oClock in the open air. . . the quick-silver 
mercuria fell to 21 D. below the freezing point [11° F].” Clark (left) called the weather “dredfull” with the wind blowing “off the Sand with fury as to Almost darken the atmespear” adding to the “agutatuion” of the Missouri River.
While the finer points matter little to armchair history buffs, what has been puzzling academics since was Clark’s reference to the “Doneyan Co.” thermometer. Many historians credit St. Louis physician, Dr, Antoine Francois Saugrain, with producing the expedition’s thermometers in Gallipolis, Ohio. Citing Clark’s reference, others contend the thermometers were probably purchased in Philadelphia from the Donegan Company They’d been in business there since 1785. And then again, maybe it was just a case of Captain Clark’s poor handwriting. bad spelling or the use of a generic name he was familiar with.
Saugrian (right) did provide medical supplies to Lewis and Clark in 1804. The first physician west of the Mississippi, he was educated in Paris and was knowledgeable in mineralogy, physics and chemistry as well as medicine. In addition, he prepared some of the expedition’s early samples for transport back to Washington and yes, he apparently also manufactured both thermometers and barometers.
The equipment’s provenance is perhaps less important than its accuracy. The explorers kept temperature readings at a number of places along their way west. It has provided today’s scientists with a reasonably reliable benchmark for climate history. 
Painting depicting Fort Mandan’s proximity to the river
So was it actually colder in 1804 than today? Maybe. January is still the coldest month in North Dakota. The most recent weather data puts North Dakota’s average daytime high at 21ºF and the average low at -6ºF. Clark’s daytime reading of 11º F would be slightly below average by today’s standards.
But Clark couldn’t calculate wind chill. The concept of the wind speed combined with air temperature was first introduced by Antarctic explorers Paul Siple and Charles Passel in 1945. It was widely used by the military before entering the public’s consciousness by way of the National Oceanic and Atmospheric Center. While the modern “chilly chart” isn’t absolutely precise, it does account for wind velocity on loss of body heat which no doubt factored into Clark’s characterization of the day as “dredfull.”
Explorers Paul Siple and Charles Passel
Absent a true reading of wind speed, it leaves the Captain’s “feels like” temperature as simple conjecture. Using his description of the atmospheric conditions, however, gusts of 35 mph could “agitate” the river as he described. That would make the wind chill somewhere around -14ºF. Winter gusts of 50 mph, certainly not unheard of in the upper Midwest, could actually make it feel like -17ºF. Cold – no matter who supplied the thermometer.
Fort Mandan Historic Site and the Lewis and Clark Interpretive Center, Washburn, N.D., provide a look back at the winter of 1804-05 for the men of the Corps of Discovery. 
The original fort was destroyed by fire before Lewis and Clark’s return in 1806 but today’s faithful reconstruction which includes the fully furnished quarters is just a stone’s throw away from its historic location. Fort Mandan is open 9 to 5 daily from April through October, closed November through March.
In addition, the newly remodeled Interpretive Center displays a collection of artifacts from the Lewis and Clark journey plus new exhibits on North Dakota history. Its open daily from 9 to 5 during the summer, closed Sundays from October through March. Admission is $7.50, $5 with North Dakota State Park Pass and includes both Fort Mandan and the Interpretive Center. For more information go to fortmandan.com, e-mail lcic@nd.gov, call (701) 462-8535, or write Interpretive Center, PO Box 708, Washburn, ND 58577-0708,
© Text Only – 2018 – Headin’ West LLC – All photos – public domain and fair use.
*Head On West strives for historic accuracy and uses a number of sources considered reliable. When research differs on significant facts, the various points of view will be cited.