Ferdinand Hassler: 1770–1843

"The Proper Person"

Historic painting of a balding 19th-century man

Lithograph by Charles Fenderich
from a painting by Wm. G. Williams (c. 1835)
Image theb3475, NOAA People Collection
Courtesy, Association of Commissioned Officers.

Ferdinand Rudolph Hassler (1770-1843) was the person selected to complete the longitude calculations from the observational data that Lewis and Clark brought back. Upon him rested the ultimate materialization of Jefferson's plan for a map of the Missouri and Columbia Rivers that would be as accurate as modern science could produce. Upon him also rested much of the blame for the plan's failure.

Hassler was born in Switzerland where, as a youth in Bern, he studied mathematics, astronomy, and surveying. He emigrated to the U.S. in 1805, and soon became associated with Robert Patterson, and John Vaughan of the American Philosophical Society. When Congress established the United States Coast Survey in 1807, Hassler was hired as supervisor, on Patterson's recommendation. Meanwhile, President Jefferson appointed him as Acting Professor of Mathematics at the new U. S. Military Academy. He was dismissed on December 31, 1809, after the new Secretary of War, John Calhoun, discovered that Congress had not authorized the hiring of civilians to staff the Academy. For the next three years he taught mathematics and Natural Philosophy at Union College in Schenectady, New York.

He was unpopular as a teacher, and was dismissed as the first superintendent of the U.S. Coast Survey after only two years in that very important position. From 1817 until 1830, however, he proved his worth as a theorist, publishing two influential books, Elements of Analytical Trigonometry, and Elements of Arithmetik, Theoretical and Practical. In 1830, President Andrew Jackson appointed him United States gauger, responsible for regulating the national standards of weights and measures. Meanwhile, he was reappointed as superintendent of the United States Coast Survey in 1832, and served successfully in that role also, until his death in 1843.

At Jefferson's behest Lewis evidently delivered at least some of his and Clark's records of celestial observations to Hassler early in the spring of 1807, for on May 3rd he advanced the mathematician $100 to begin computing the longitudes. On 26 January 1810, three months after Lewis's death, Clark wrote to Hassler: "The Calculations which you made of the Celistial Observations taken by the late Govr. Lewis (& myself) on the late expedition to the Pacific, are not found among his papers. . . . I flatter my self with a hope that those Calculations with the M[em]orandoms are in your possession." He requested that Hassler send them to the publisher who was to issue the journals, John Conrad of Philadelphia. Nearly seven months later Hassler sent the following letter to his friend Robert Patterson, still uncertain as to what had been expected of him. (A copy of a map by Clark was immediately forwarded to him; Hassler returned it to Nicholas Biddle, but it has since been lost.) By the following December 20th, despite the free time the mathematician expected to have in late August, Clark had given up. "I am sorry that I could not get the Calculations from Mr. Hosler[sic] to Correct the Map," he wrote to Biddle, "but, I hope [the final map] will doe without." Biddle was exasperated with Hassler too, as the next letter suggests.

Hassler's work with Lewis and Clark's celestial observations was intermittent and perfunctory, which made it unproductive in the long run. It was unsatisfying to all concerned, for reasons which are implied in the two letters that follow. Hassler's writing is sometimes difficult to understand, owing to his somewhat limited facility with the English language.


Florian Cajori, The Chequered Career of Ferdinand Rudolph Hassler (Boston: Christopher Publishing House,1929).

V. Frederick Rickey, "Ferdinand Rudolph Hassler," A Station Favorable to the Pursuits of Science: Primary Materials in the History of Mathematics at the U.S. Military Academy

Funded in part by a grant from the NPS Challenge-Cost Share Program