In 1854 he delivered a series of twelve lectures on English poetry before the Lowell Institute. Ten years before he had published a volume of "Conversations on the Poets." The contrast between the two works is no less pronounced than that between his earlier and later poems. In both, however, there is a tendency toward a confusing over-elaboration--Metaphors trample on the heels of Similes, and quaint and often grotesque conceits sometimes pall upon the taste, just as in the poems a flash of incongruous wit sometimes disturbs the serenity that is desirable. On his return from Europe, Mr. Lowell occupied the chair which he adorned by his brilliant attainments and made memorable by his fame. He lectured on Dante, Shakespeare, Chaucer, and Cervantes, and delighted his audiences. At the same time he was editor of the _Atlantic Monthly_ for several years. From 1863 until 1872 he was associated with Professor Charles Eliot Norton in the conduct of the _North American Review_. In 1857 he married Miss Frances Dunlap of Portland, Me., a cultivated lady who had been the governess of his daughter. She had unerring literary taste and sound judgment, and Mr. Lowell soon came to entrust to her the management of his financial affairs. She was enabled to make their comparatively small income more than meet the exigencies of an exacting position. The second series of the "Biglow Papers," relating to the War of the Rebellion, were first published in the _Atlantic_. They were collected into a volume in 1865. That year was rendered notable by his "Commemoration Ode," the worthy crowning of one of the grandest poetic opportunities ever granted to man. "Under the Willows" appeared in 1869; "The Cathedral" in 1870. In 1864 he had issued a collection of his early descriptive articles under the title, "Fireside Travels." In 1870 came "Among my Books." The second series followed in 1876. "My Study Windows" was published in 1871. All these prose works were marked by an exuberant, vivid, poetic, impassioned style. The tropical efflorescence of imagery was characteristic of them all. He ought to have remembered his own words,-- "Over-ornament ruins both poem and prose." In 1876 appeared three memorial poems: that read at Concord, April 19, 1875; that read at Cambridge under the Washington Elm, July 3, 1875; and the Fourth of July Ode of 1876. This year Mr. Lowell was appointed one of the presidential electors; and the following year President Hayes first offered him the Austrian mission, and, on his refusal of that, gave him the honorary post at Madrid, which had been adorned by Everett, Irving, and Prescott. He was there three years, and, on the retirement of Mr. Welsh in 1880, was transferred to the Court of St. James, or, as one of the English papers expressed it, he became "His Excellency the Ambassador of American Literature to the Court of Shakespeare."