The Phrenologist. Phrenology, the assessment of a subject's mental faculties by study of the external conformation of the cranium. The phrenologist feels his own cranial bumps with one hand while holding a skull in the other. A book on phrenology is open on the table and on the floor are ceramic heads numbered with the areas of the head applying to various characteristics. Lithograph published in 1830 when phrenology was popular.