Those of a warm and peaceful disposition should, in theory, find the second area of their skull flatter than the first. But don't be too concerned if your bumps do not match your self-perceptions - Gall derived his chart largely from feeling the heads of his local vicar and two recently widowed and "emotional" women neighbours. It was dubious methodology even for the early 19th century.
This did not stop phrenology from catching on. By mid-century every major American city had its Phrenology Institute, illnesses were diagnosed by head- feelers, and companies had potential employees "read" by a phrenologist before they were taken on. Feeling each others' bumps was a jolly way to spend a rainy evening, and even Queen Victoria had her children's heads "read".
Meanwhile brain analysis of a different kind was catching on in universities. New, powerful microscopes gave rise to a fashion for anatomical dissection, and neurologists - including the young Freud - were scrutinising brain tissue for clues to the physical roots of behaviour.
Dead brain tissue alone offers few clues to its function in life, however. In order to chart behaviour to a specific physical location scientists sought people whose behaviour was changed by cerebral accidents. Pierre Broca found the ideal patient: Tan. Tan was called Tan because that was what he said when asked his name. It was also what he said when he was asked where he lived . . . and what he would like for dinner. Tan was all that Tan could say, and his monosyllabic utterings comprised the first case of what is now known as "Broca's aphasia".
The condition was caused - as Broca subsequently discovered - by damage to an area of cortex on the left side of the brain, just in front of and above the ear. This patch of tissue carries his name to this day.
In laying claim to the first recognised brain "module" Broca initiated the still incomplete task of mapping the human mind. He also put the first nail in the coffin of phrenology because the area he identified as a language module was the phrenological "Organ of Acquisitiveness". In that first territorial battle for the landscape of the mind science triumphed - and the porcelain phrenology head became a junkshop relic.
Today the task of charting the human brain is helped by imaging machines which allow scientists to look inside the skull and see precisely how the brain constructs thoughts, feelings and perceptions. These studies show that the phrenologists were correct in saying the brain is a collection of organs - they were wrong only in thinking that such organs bore any relation to bumps on the head.
Yet Gall's map was not entirely inaccurate. Earlier this year, as part of a surgical procedure to relieve epilepsy, neurologists in California used an electrode to stimulate a spot on the cortex of a 16-year-old girl. Immediately the girl (who was conscious) started to giggle. Asked why she told the surgeons: "it's just so funny . . . you guys . . ." When the stimulation stopped she stopped finding it funny. When it was started again she resumed giggling.
The spot that produced this reaction was on the left side of her head, two or three inches above Broca's area. Look it up in a phrenology head and you will see that it is marked the "Organ of Amusement".
Rita Carter is the author of `Mapping the Mind' (Weidenfeld and Nicolson, pounds 25). An ICA/Royal Institution seminar on `Mapping the Mind' will be held at the Royal Institution, 21 Albemarle Street, London W1, on 10 November at 7pm; tickets from the ICA box office, 0171-930 3647