(1795–1856), born in Connecticut, graduated from Yale (1815), studied for his M.D. at the University of Pennsylvania and Yale, had a brief career as a doctor, was a journalist in South Carolina, Connecticut, and New York, and taught chemistry at West Point. He chiefly fancied himself as a romantic poet, and for a time shared this conviction with others, enjoying a great vogue until the ascendancy of Bryant. Percival's Poems (1821) includes the long Spenserian Prometheus, accounted by his compatriots the equal of Childe Harold; Clio (3 vols., 1822–27) consists of dream-haunted soliloquies; and The Dream of a Day (1843), with more prosaic subjects, is noted for its metrical experimentation. Although he was a man of unquestionable intellect, he was a lifelong eccentric and paranoiac, and for some time resided by his own choice in the New Haven State Hospital. He shuttled pathetically between various professions, but failed to attain greatness in any of them. Besides being an able linguist and philologist he served as state geologist of Connecticut (1835–42) and Wisconsin (1854–56), gathering much scientific information and formulating at least one important geological law.
From The Oxford Companion to American Literature in Oxford Reference.