Dr. Charles Caldwell, who graduated with his medical degree in 1796 also rose to prominence in the American School. His publication Phrenology vindicated, and Antiphrenology Unmasked (1838) supported Samuel Morton’s claims. Caldwell also advanced the belief that slavery was natural.
The physicians of the American School often corresponded with Southern political leaders. In Types of Mankind, Josiah Nott proudly notes Morton’s influence on the prominent South Carolinian Fire Eater John C. Calhoun:
‘A Correspondence ensued between Mr. Calhoun and Dr. Morton on the subject, and the Doctor presented to him copies of the Crania Americana… which Mr. Calhoun studied with no less pleasure than profit.’
The ‘Correspondence’ Josiah Nott references began in 1844 when Calhoun was serving as a Secretary of State; Samuel Morton meanwhile had retired from his professorship at Penn a few months prior. According to Nott, Calhoun began corresponding with Morton because he believed that:
‘England pertinaciously continued to interfere with our inherited Institution of Negro Slavey’ and ‘although he could not foresee what course the negotiation might take, (he) wished to be forearmed for any emergency.’ Morton’s Crania Americana, published while he was a professor at Penn, therefore served to influence policy debates on a national level during the Antebellum period.