(b. Wilmington, Delaware, 4 March 1792;d. Philadelphia, Pennsylvania, 8 December 1886)
The fifth son of James Lea, a Quaker merchant of Wilmington, Isaac attended the local academy with the idea of becoming a physician; but at the age of fifteen he went to work in the Philadelphia mercantile business of his brother John, who eventually made him a partner.In Philadelphia, Lea formed a lifelong friendship with Lardner Vanuxem, with whom he roamed the countryside collecting minerals, rocks, and fossils. They were both elected to the Academy of Natural Sciences of Philadelphia in 1815; and in 1818 Lea published in its Journal his first scientific paper, “An Account of the Minerals at Present Known to Exist in the Vicinity of Philadelphia.” The study of geology led to the study of shells, and Lea spent several years studying the collections of freshwater mollusks that Major Stephen Long had sent to the Academy from the Ohio River and that his brother Thomas Lea had gathered for him near Cincinnati. In 1827 he published, in Transactions of the American Philosophical Society, “A Description of Six New Species of the Genus Unio.” Thereafter he devoted most of his scientific attention to “this truly seducing branch of Nat: Hist.” His Contributions to Geology (Philadelphia, 1833), a descriptive catalogue principally of specimens of the Tertiary formations at Claiborne, Alabama, firmly established his reputation. Its text was distinguished by care and judgment; and its typography and illustrations, Roderick Murchison told the author, had “quite the stamp of being issued by one of the best workshops of Europe.”
The subject was well chosen, for although mollusks abounded in American rivers, scarcely anyone had searched for them there. An acute and accurate observer, during a long lifetime Lea collected, identified, and described, chiefly in papers to the Academy of Natural Sciences and the American Philosophical Society, 1,842 species of some fifty genera of freshwater and terrestrial mollusks. “I sometimes fear I take up too much room in the Society’s Transactions,” he once half-apologized, “but it is a great matter to have new objects of Natural History well illustrated—it saves hundreds of mistakes which in time might otherwise occur.” In addition to shells, Lea figured the embryonic forms of thirty-eight species of Unio and described the soft parts of another 234. His Synopsis of the Family of Naiades (Philadelphia-London, 1836; 4th ed. 1870) classified the synonymy of the Unionidae, until then in great confusion. He also investigated physiological questions, such as mollusks’ sensitivity to light and differences due to sex. Lea ordered 250 reprints of each paper, bound them up from time to time with title page and introduction as Observations on the Genus Unio (13 vols., 1827-1874), and presented them to institutions and individuals. “Your intelligent perseverance with consummate skill & taste have reared a brilliant monument in this part of conchology,” the elder Silliman told him in 1860 in acknowledging one of these volumes. Lea’s bibliography, compiled in 1876, contained 279 titles.
Lea’s personal collection was steadily augmented by gifts from other naturalists—among them Jeffries Wyman, Charles M. Wheatley, Bishop Stephen Elliott, Gerard Troost, John LeConte, and Dr. John Kirk, who accompanied Livingstone to Lake Nyassa. After seeing Lea’s cabinet in 1846, Agassiz declared “that all which European naturalists have written on this subject must be revised.” Captain Frederick Marryat pronounced it “certainly the most interesting “museum” I saw in the States” and a principal reason why Philadelphia, not Boston, must be considered “the most scientific city in the Union.” In his later years Lea turned to the study of crystals and is said to have been the first in America to engage in microscopic mineralogy.
Unlike those of some contemporaries, Lea’s disputes with fellow scientists were never acrimonious. He thought Rafinesque’s descriptions “very imperfect”; and in a “rectification”of T. A. Conrad’s errors and omissions, he asserted his own claims to priority in discoveries (1854). His report on the footprints of the reptile Sauropus primaevus in the Old Red Sandstone was disputed by Agassiz, who asserted that no air-breathing animals had existed earlier than the new Red Sandstone. Lea maintained his position in a carefully argued and illustrated monograph, which he ultimately reproduced in elephant folio, with a lithograph of the footprint in actual size. Of some importance then, the matter is of less concern now that fossils of air-breathers have been found in other formations.
Lea was a striking example of the self-taught amateur who by single-minded attention to a limited subject makes a comprehensive, basic, and lasting contribution to knowledge. He expressed the spirit that guided him in 1826: “To scrutinize the first cause is vain; we must make ourselves acquainted with the effects and compare them. In this we have ample room to engage all our faculties.”Lea served as president of the Academy of Natural Sciences, vice-president of the American Philosophical Society (where he was also chairman of the finance and publications committees), and president of the American Association for the Advancement of Science. He received an honorary LL.D. from Harvard in 1852 and was a member or fellow of a score of foreign academies. On visits of England and in 1832 and 1852-1853 he was warmly received by Alexander von Humboldt, William Buckland, Charles Lyell, Roderick Murchison, and Adam Sedgwick; and he inspected and named specimens of Unionidae in the British Museum, the Jardin des Plantes, and private collections.
Lea did his scientific work at the end of days filled with business and social obligations. Having joined Mathew Carey’s publishing firm in 1821 after his marriage to Carey’s daughter Frances Anne, he eventually became president, but retired in 1851. He was rich, with the obligations that wealth entails. Commenting on several unexpected family deaths that left him in 1845 responsible for the children of four relatives, he exclaimed to J. C. Jay, “God knows when I shall have leisure to pursue my wishes in our beautiful branch of Science.” Of his three children, M. Carey Lea was a pioneer in photochemistry; and Henry Charles Lea, whose first published paper was on shells, became, after retiring from the publishing firm, the historian of the Inquisition. Lea bequeathed his collection, numbering nearly 10,000 specimens, to the National Museum, Washington.
I. Original Works. Lea’s contributions are analyzed in Newton P. Scudder, Published Writings of Isaac Lea, LL.D., Bulletin. United States National Museum, no. 23 (Washington, D.C., 1885). The Academy of Natural Sciences of Philadelphia and the American Philosophical Society Library possess correspondence used in this sketch. Lea’s journals of foreign travel are available on film at the American Philosophical Society Library.
II. Secondary Literature. The principal biographical sketch is by Newton P. Scudder, introducing Lea’s Published Writings, cited above. For other data see “A Sketch of the History of Conchology in the United States,” in American Journal of Science and Arts, 2nd ser.,33 (1862), 161-180; W. H. Dall, “Isaac Lea, LL.D.,” inScience,8 (17 Dec. 1886), 556-558; Joseph Leidy, “Biographical Notice,” in Proceedings of the American Philosophical Society,24 (1887), 400-403; and W. J. Youmans, Pioneers of Science in America (New York, 1896), 260-269.
Whitfield J. Bell, Jr.