Charlotte Brontë frequently makes use of physiognomy and phrenology in describing her characters. Do we know of any sources where she might have learned about it? They would be interesting references to have on hand while reading her books. Sources that Brontë herself might have read, rather than any and all that were available in her time, are of particular interest to me. Note – I'm aware that these "disciplines" were unscientific and often very racist. I'm only looking to learn more about them to enhance my understanding of Brontë's character descriptions.
According to a recent paper (Tytler, 2019) on the subject, Charlotte Brontë's fascination with physiognomy and phrenology were likely inspired by Johann Casper Lavater's Physiognomische Fragmente (Essays on Physiognomy), which caught on in English literature through the influence of Sir Walter Scott.
This paper examines her first novel, The Professor, finding thematic similarities between the type of physiognomic analyses employed by the protagonist, William Crimsworth, and the ideas and applications of physiognomy in Scott and Lavater.
And though Lavaterian ideas may also be discerned outside contexts of the composite portrait in the works of, say, Ann Radcliffe, ‘Monk’ Lewis and William Godwin, it is principally in Sir Walter Scott’s fiction that such ideas are to be found in abundance. It is for this very reason that Scott may be rightly deemed a watershed figure in the history of the relationship between physiognomy and the modern novel. Charlotte Bronte was, as is well known, a great admirer of Scott’s writings, and there can be no question but that she was much indebted to him for her own treatment of the outward person in her novels. This would appear to be especially true of her uses of three aspects of physiognomy which, prominent enough in Scott’s narratives, had already been specially pointed up and even partly illustrated in Lavater’s Essays: the national physiognomy, the family physiognomy and the social physiognomy. The same may be justly said of those contexts in The Professor where individuals are described in highly analytical detail, where physiognomic judgements are made and where physiognomic discussions take place.
Tytler, Graeme. "Physiognomy in The Professor." Brontë Studies 44.4 (2019): 339-350.