Astro-Phrenological chart, from "The magic of the cards: Giving the mystic meaning of these wonderful and ancient emblems in their relationship to the heavenly bodies, under all conditions; with rules and processes for reading or delineating the emblems" by Olney H. Richmond, 1919.

Phrenology is a process that involves observing and/or feeling the skull to determine an individual’s psychological attributes. Franz Joseph Gall believed that the brain was made up of 27 individual organs that determined personality, the first 19 of these ‘organs’ he believed to exist in other animal species. Phrenologists would run their fingertips and palms over the skulls of their patients to feel for enlargements or indentations. The phrenologist would often take measurements with a tape measure of the overall head size. The phrenologists put emphasis on using drawings of individuals with particular traits, to determine the character of the person and thus many phrenology books show pictures of subjects. From absolute and relative sizes of the skull the phrenologist would assess the character and temperament of the patient.