From the great degree of insensibility which prevails in some states of madness, a degree of cold would scarcely be felt by such persons, which would create uneasiness in those of sound mind; but experience has shewn that they suffer equally from severity of weather. When the mind is particularly engaged on any subject, external circumstances affect us less than when unoccupied. Every one must recollect that, in following up a favourite pursuit, his fire has burned out, without his being sensible of the alteration of temperature; but when the performance has been finished, or he has become indifferent to it from fatigue, he then becomes sensible to cold, which he had not experienced before. Some maniacs refuse all covering, but these are not common occurrences; and it may be presumed, that by a continued exposure to the atmosphere, such persons might sustain, with impunity, a low temperature, which would be productive of serious injury to those who are clad according to the exigences of the season. Such endurance of cold is more probably the effect of habit, than of any condition peculiar to insanity. Having thus given a general account of the symptoms, I shall now lay before my readers a history of the appearances which I have noticed on opening the heads of several maniacs who have died in Bethlem Hospital. CHAP. III. CASES, WITH THE APPEARANCES ON DISSECTION. CASE I. J. H. a man twenty-eight years of age, was admitted a patient in May, 1795. He had been disordered for about two months before he came into the hospital. No particular cause was stated to have brought on the complaint. It was most probably an hereditary affection, as his father had been several times insane and confined in our hospital. During the time he was in the house, he was in a very low and melancholic state; shewed an aversion to food, and said he was resolved to die. His obstinacy in refusing all nourishment was very great, and it was with much difficulty forced upon him. He continued in this state, but became daily weaker and more emaciated until August 1st, when he died. Upon opening the head, the pericranium was found loosely adherent to the scull. The bones of the cranium were thick. The pia mater was loaded with blood, and the medullary substance, when cut into, was full of bloody points. The pineal gland contained a large quantity of gritty matter.[8] The consistence of the brain was natural; he was opened twenty-four hours after death. CASE II.