The journals for July 18, 1805 capture a pivot in the expedition’s progress up the Missouri above the Great Falls. The corps named a substantial tributary, Captain Clark departed overland with a small party to seek the Shoshone, and the main body labored against an increasingly swift current. Patrick Gass, Meriwether Lewis, and William Clark each recorded the day, and read together their entries reveal not only a shared chronology but a triangulated portrait of geography, intent, and observation.
One River, Three Measurements
All three narrators record the entrance of the stream the captains christened Dearborn’s River, after Secretary of War Henry Dearborn. The naming itself is consistent across Lewis and Clark, but the descriptive registers diverge sharply. Lewis offers the fullest treatment, locating the confluence and characterizing the water:
at the distance of 21/2 miles we passed the entrance of a considerable river on the Stard. side; about 80 yds. wide being nearly as wide as the Missouri at that place. it’s current is rapid and water extreamly transparent; the bed is formed of small smooth stones of flat rounded or other figures.
Clark, writing in his characteristically compressed field hand, echoes Lewis nearly verbatim on the essentials — “a Considerable river which falls in on the Stard Side and nearly as wide as the Missouri” — but omits the bed composition and the transparency of the water. Gass, working at a further remove from the captains’ cartographic concerns, does not name Dearborn’s River at all. Instead he logs an unnamed “Clear-water river on the north side about 50 yards wide, rapid and shallow,” almost certainly the same stream, with a width estimate notably smaller than Lewis’s eighty yards. The discrepancy is typical: Gass, whose journal was prepared for a wider readership, regularly approximates where Lewis measures.
The Advance Party and the Shoshone Problem
The day’s strategic decision — to send Clark ahead with a small detachment — appears in both captains’ journals with closely matching reasoning. Lewis explains at length:
as we were anxious now to meet with the Sosonees or snake Indians as soon as possible in order to obtain information relative to the geography of the country and also if necessary, some horses we thought it better for one of us either Capt. C. or myself to take a small party & proceed on up the river, some distance before the canoes, in order to discover them, should they be on the river before the daily discharge of our guns … should allarm and cause them to retreat to the mountains.
Clark records the same logic in shorthand: “we thought it prudent for a partey to go a head for fear our fireing Should allarm the Indians and cause them to leave the river and take to the mountains for Safty from their enemes who visit them thro this rout.” The phrasing is close enough — “allarm,” “take to the mountains” — to suggest the captains discussed the rationale together before each wrote it down. Gass, by contrast, registers only the bare fact: “At breakfast time Captain Clarke with three men went on ahead.” He names no purpose, no Shoshone, no anxiety about gunfire. The strategic frame belongs to the captains; the sergeant logs the personnel movement.
What Each Narrator Notices Alone
The most striking divergences emerge in what each man chose to record beyond the shared events. Lewis devotes a long passage to the bighorn sheep he watched at dawn, bounding on a near-perpendicular cliff “where it appared to me that no quadruped could have stood,” and a second to a wild flax he believed might “yeald good flax” comparable to the cultivated American crop — the naturalist and the political economist working in tandem. Neither Clark nor Gass mentions either subject.
Clark, traveling overland on “an Indian rode” that cut off several meanderings of the river, contributes the day’s only ethnographic infrastructure note: the road “is wide and appears to have been dug in maney places.” He alone observes that the smaller streams “are darned up by the beaver from near ther mouthes up as high as I could See up them,” and he alone identifies the timber as “principally pitch pine.” His vantage from the ridge gave him a synoptic view the canoe party lacked.
Gass, confined to the river, offers what the captains omit: a clean total. “We made 20 miles this day.” He also notes the small detail that the advance party left a deer skin hung as a sign for the boats to find — a quotidian act of woodcraft that neither captain bothered to record. Across the three entries, the same July day becomes a layered document: Lewis the observer of species, Clark the reader of terrain and sign, Gass the keeper of distance and the small mercies of trail communication.
