On July 4, 1805, Meriwether Lewis wrote that since their arrival at the Great Falls of the Missouri River on June 13 they had:
repeatedly witnessed a nois which proceeds from a direction a little to the N. of West as loud and resembling precisely the discharge of a piece of ordinance of 6 pounds at the distance of three miles. I was informed of it by the men several times before I paid any attention to it, thinking it was thunder most probably which they had mistaken. At length, walking in the plains the other day I heard this noise very distinctly. It was perfectly calm, clear, and not a cloud to be seen.
"I am at a loss to account for this phenomenon," he mused, but he reassured himself with the confidence of a true son of the Age of Enlightenment: "I have no doubt but if I had leasure I could find from whence it issued."
On July 11 Lewis recorded two more discharges of this "unaccountable artillery of the Rocky Mountains." He recalled that Pawnee and Arikara Indians far down the Missouri had mentioned just such a mysterious noise coming from the Black Hills in present-day South Dakota, but he had paid no attention, supposing the rumor to be either false or "the fantom of a supersticious immagination." The trader Jean Vallé, whose house at the mouth of the Cheyenne River they visited the previous October, had also told them that near the river's sources in the Black Hills "a great noise is heard frequently."
William Clark summarized Lewis's notes on the matter. "It is probable," he added, "that the large river just above those Great falls which heads in the derection of the noise has taken it's name Medicine River [today's Sun River] from this unaccountable rumbling sound, which like all unacountable thing with the indians of the Missouri is Called Medicine."1 After the expedition ended, there was some more discussion about it between Clark and Nicholas Biddle, the editor of the History of the Expedition. On December 20, 1810, Clark wrote to Biddle: "I think I mentioned having heard a rumbling noise at the falls of the Missouri, which was not accounted for, and you accounted for them by similating them to Avelanches of the Alps." Biddle must have had second thoughts about his own suggestion, however, for no such notion appeared in the History, which was published in 1814.2
The sound of "artillery" continued to startle travelers in the West. The information the Pawnees and Arikaras gave to Lewis was reconfirmed in 1810 by Wilson Price Hunt, who was in charge of John Jacob Astor's Pacific Fur Company expedition to the mouth of the Columbia River. Meriwether Lewis's younger contemporary, Washington Irving (1783-1859), who related the account in his history of the Astor family, Astoria, said that Hunt reported a "natural phenomenon of a singular nature" in the vicinity of the Black Hills. Similar sounds, Hunt remarked, had been heard in several parts of Brazil by a Jesuit priest named Vasconcelles, who was told by the Indians there that it was "the throes and groans of the mountain endeavoring to cast forth the precious stones hidden within its entrails." In fact, Irving continued, "these singular explosions have received fanciful explanations from learned men, and have not been satisfactorily accounted for even by philosophers."3
1. Donald Jackson, ed, Letters of the Lewis and Clark Expedition with Related Documents 2nd ed., 2 vols. (Urbana: University of Illinois Press, 1978), p. 565.
2. Paul Allen, History of the Expedition Under the Command of Captains Lewis and Clark, to the Sources of the Missouri, Thence Across the Rocky Mountains and Down the River Columbia to the Pacific Ocean, 2 vols. (Philadelphia: Bradford and Inskeep, 1814).
3. Washington Irving, Astoria, Or Anecdotes of an Enterprize Beyond the Rocky Mountains, in Richard Dilworth Rust, ed., The Complete Works of Washington Irving (1836; reprint, Boston: Twayne Publishers, 1976), I:167. In the 18th century a philosopher was, in general, a learned person or a scholar. Adam Smith (1723-1790), the Scottish student of political economy, described philosophers as "men of speculation, whose trade is, not to do any thing, but to observe every thing." Smith, An inquiry into the nature and causes of the wealth of nations (1776); Penn State Electronic Classics Series Publication, p. 15.