Documents Archive - Lewis & Clark Research Database

Lewis’s Astronomical Observations and Calculations

Tue, 10 Feb 2026 13:58:29 +0000

Lewis was trained in celestial navigation by Andrew Ellicott and Robert Patterson before the expedition. Using a sextant, chronometer, and artificial horizon, he recorded observations of the sun, moon, and stars at numerous points along the route to calculate latitude and longitude. The observations were essential for Clark’s mapmaking. After the expedition, the raw data was sent to mathematician Ferdinand Hassler for computation, but publication was delayed for years. Some original observation notebooks have been lost.

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Land Warrants Issued to Expedition Members

Tue, 10 Feb 2026 13:58:29 +0000

On March 3, 1807, Congress passed an act granting double pay and land warrants to the members of the expedition. Captains Lewis and Clark received 1,600 acres each; enlisted men received 320 acres each. Many soldiers sold their land warrants rather than settling on them. The land grants were located in the Louisiana Territory, making the expedition members some of the earliest American landholders in the trans-Mississippi West. The compensation reflected Congressional recognition of the extraordinary dangers and achievements of the expedition.

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Court Martial Proceedings of the Expedition

Tue, 10 Feb 2026 13:58:29 +0000

Military discipline was essential to the expedition’s survival, and Lewis and Clark maintained a formal court martial system throughout the journey. Private Moses Reed was found guilty of desertion in August 1804 and was “run through the gauntlet” four times and discharged from the permanent party. Private John Newman was court-martialed for mutinous expression and similarly punished. Several soldiers were disciplined for drunkenness, sleeping on guard duty, and insubordination. These proceedings demonstrate the military structure that undergirded the expedition.

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Lewis’s Descriptions of New Animal Species

Tue, 10 Feb 2026 13:58:29 +0000

Among the most notable species described were the grizzly bear (Ursus arctos horribilis) — which nearly killed several expedition members — the pronghorn antelope, the black-tailed prairie dog (live specimens of which were sent to Jefferson), the cutthroat trout, the eulachon (candlefish), the mountain quail, Lewis’s woodpecker, Clark’s nutcracker, and the Oregon bobcat. Lewis’s detailed physical descriptions and behavioral observations provided the basis for scientific classification by naturalists including George Ord, Alexander Wilson, and Charles Lucien Bonaparte.

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Lewis’s Descriptions of New Plant Species

Tue, 10 Feb 2026 13:58:29 +0000

Lewis received botanical training from Benjamin Smith Barton at the University of Pennsylvania before the expedition. Throughout the journey, he collected and described specimens including Lewis’s monkey-flower (Mimulus lewisii), bitterroot (Lewisia rediviva — Montana’s state flower), Clarkia (named for William Clark), and dozens of other species. His pressed specimens were sent to the American Philosophical Society and the Academy of Natural Sciences. Botanist Frederick Pursh published scientific descriptions of many Lewis specimens in his “Flora Americae Septentrionalis” (1814).

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Jefferson’s Message to Congress on the Expedition’s Return

Tue, 10 Feb 2026 13:58:29 +0000

Jefferson presented to Congress Lewis’s summary of the expedition’s findings, including estimates of Native populations, trade potential, and geographical observations. He requested that Congress grant double pay and 320 acres of land to each expedition member, reflecting the dangers and hardships they had endured. Congress approved these awards, making the expedition members some of the first recipients of public land grants west of the Mississippi.

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History of the Expedition Under the Command of Captains Lewis and Clark (Biddle Edition)

Tue, 10 Feb 2026 13:58:29 +0000

After Lewis’s death in 1809 left the journals unpublished, Clark entrusted them to Biddle, who produced a readable narrative from the raw journal entries. The two-volume work included Clark’s map but omitted most scientific observations. It was not a commercial success, partly because eight years had passed since the expedition’s return and public interest had waned. Only 1,417 copies were printed, and the publishers went bankrupt. Despite its initial poor sales, the Biddle edition remained the standard account until the Thwaites scholarly edition of 1904-1905.

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Clark’s Map of the American West (1810)

Tue, 10 Feb 2026 13:58:28 +0000

Clark drew maps throughout the expedition, eventually compiling them into a master manuscript map that depicted the entire route from St. Louis to the Pacific. Published as an engraved version by Samuel Lewis in the 1814 Biddle edition, the map remained the primary cartographic reference for the American West until the railroad surveys of the 1850s. Clark’s maps were remarkably accurate given the instruments available, though they compressed the width of the Rocky Mountains.

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Clark’s Letter to Brother Jonathan Announcing Return

Tue, 10 Feb 2026 13:58:28 +0000

Clark wrote to Jonathan from St. Louis on September 23, 1806, the day of their triumphant return. His letter provided personal details about the journey that he would not have included in official correspondence, including observations about individual expedition members, the physical toll of the journey, and his plans for the future. Clark’s correspondence with his family provides important context for understanding the personal side of the expedition.

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Lewis’s Letter to Jefferson Announcing the Expedition’s Return

Tue, 10 Feb 2026 13:58:28 +0000

Writing from St. Louis, Lewis summarized the expedition’s key findings: “In obedience to your orders we have penetrated the Continent of North America to the Pacific Ocean.” He described the route, the Native nations encountered, and the prospects for American commerce in the West. Lewis reported that the all-water route to the Pacific that Jefferson hoped for did not exist — the Rocky Mountains proved to be a formidable barrier requiring an overland portage. The letter was widely reprinted and made Lewis and Clark national celebrities overnight.

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