In the book The Fifth American Chess Congress published by Charles Gilberg in 1889 there was an interesting article, Phrenological Character of Mr. Louis Paulsen by L.N. Fowler, a Professor of Phrenology.
Phrenology was a pseudo-medicine that focused on measuring the skull. It was developed by German physician Franz Joseph Gall in 1796 and became very popular in the 1800s. Gall's assumption was that a person's character, thoughts and emotions are located in specific parts of the brain. Although it has a basis in reality, phrenology taught that you could know a person's mental capabilities based on skull measurements.
The various areas of the brain were believed to be proportional to a person's propensities. It was believed that the cranial skull, like a glove on the hand, accommodates to the different sizes of these areas of the brain, so that a person's capacity for a given personality trait could be determined simply by measuring the area of the skull that overlies the corresponding area of the brain. See Phrenology Diagrams from Vaught’s Practical Character Reader (1902) HERE
A popular movement, especially in Europe, the intellectual elite of the United States found phrenology attractive because it provided a biological explanation of mental processes based on observation. As usual, some questioned its validity and by the 1840s there were many successful attempts to refute it and by the 1840s the practice had lost its credibility.
In the southern United States phrenology also faced an obstacle in the antislavery movement. While phrenologists usually claimed the superiority of the European race, they were often sympathetic to liberal causes including the antislavery movement; this sowed skepticism about phrenology among those who were pro-slavery.
The rise and surge in popularity in mesmerism (hypnosis) also had a hand in the loss of interest in phrenology among intellectuals and the general public.
According to Fowler, Paulsen was remarkable for the size of his brain and its separate “facilities.” The ordinary size of a male head was 22 inches, but Paulsens' was 24.5 inches.
By the way, people are bigger today than they were during Paulsen's day. Today the average head circumference for a white male is 24 inches. The average for a Latino male is 21.5 inches. The average for an Asian male is 23.6 inches. The average for an African-American male is 23 inches. Historian Bell I. Wiley, who pioneered the study of the Civil War-era common soldier, put the average soldier at about 5 feet 8 inches tall and about 143 pounds. Today the average American height for men is 5 feet 9.7 inches and 195.7 pounds according to data from 2011 to 2014. The former average, 180.7 pounds, was based on data from 1988-1994.
Paulsen's head was 2.5 inches larger than average, so by today's standards that would put it at a whopping 26.5 inches. When I checked hat size charts they only went to 25 inches. So, for his day Paulsen must have had a really big head!
One leading feature was its “ comprehensiveness, largeness and expansiveness of thought and feeling.” As a result Paulsen was said to be able to see further, carry more in his mind and more easily understand the “adaptations ans relations” than most men.
Paulsen wasn't “smart in small things,” but was at his best when he really had to think. He was prudent, very cautious and exercised restraint. He possessed tenacity and perseverance. His self-esteem and steadiness gave him a steady hand. Circumspect and consistent, Paulsen had a sense of moral obligations and was a good executive and manager and if he was interested in a subject he could give it his full attention.
Analysis showed him to be remarkably warm hearted and social. He wasn't cunning, selfish, ambitious or vain and had an unusual degree of sympathy, tender heartedness and goodwill.
He was respectful and interested in things of a spiritual and supernatural nature. Fowler also stated that Paulsen was ingenious, constructive and versatile with a lot of imagination and a sense of beauty. At the same time those characteristics were more of an intellectual nature than a “poetic” nature. While he was quick witted and enjoyed a good joke, Pauslen was not frivolous.
Paulsen's particularly large frontal lobe meant he was unusually intelligent and possessed the ability to make minute observations with a good perception of forms, faces, shapes and outlines.
With remarkable powers to plan, systematize and ability to to reach the desired results, he was able to expend as little mental energy as possible on problems. He could remember locations and the relative beatings of things after having seen them only once. But, his memory of events and dates was good, but not great. His reasoning ability was unusually strong. He wasn't given to talking much unless excited and was generally taciturn.
Fowler concluded that Paulsen's talent as a chessplayer arose first from the fact that he had a large brain of good quality. Secondly, from the fact that he was cool, prudent and had foresight. Thirdly, he was perceptive, systematic, had a good memory and was philosophical.
Fowler's final conclusion was that Paulsen's phrenological development was perfect to make him a good player.