Carlyle and High Victorian Racism

David Brion Davis considers Carlyle's 1853 pamphlet Occasional Discourses on the Nigger Question [another source cites an 1849 version published as "Occasional Discourses on the Negro Question"] - which incidentally is the source of the expression "dismal science - as symptomatic of a rebirth of "official" scientific racism displacing earlier scientific notions of racial equality:

Despite the prejudice of Hume and some other eighteenth-century writers, and in striking contrast to post-Revolutionary France, most British scientists of the early 1800s, exemplified by James Cowles Pritchard, insisted on the unity and even perfectability of all human groups. The historian Seymour Drescher makes the extraordinary point that not a single M.P. spoke of any alleged incapacity of the Negroes. But by the 1850s African American visitors in Britain, like Frederick Douglass, sensed a deeply troubling change in attitude even from the mid-1840s (symbolized by Thomas Carlyle's 1853 Occasional Discourse on the Nigger Question). (Inhuman Bondage p. 76)