J. H. a man, aged forty-two, was admitted into the house on April 12, 1794. He had then been disordered two months: it was a family disease on his father's side. Having manifested a mischievous disposition to some of his relations, he was continued in the hospital upon the incurable establishment. His temper was naturally violent, and he was easily provoked. As long as he was kept to any employment he conducted himself tolerably well; but when unoccupied, would walk about in a hurried and distracted manner, throwing out the most horrid threats and imprecations. He would often appear to be holding conversations: but these conferences always terminated in a violent quarrel between the imaginary being and himself. He constantly supposed unfriendly people were placed in different parts of the house to torment and annoy him. However violently he might be contesting any subject with these supposed enemies, if directed by the keepers to render them any assistance, he immediately gave up the dispute and went with alacrity. As he slept but little, the greatest part of the night was spent in a very noisy and riotous manner. In this state he continued until April 1796, when he was attacked with a paralytic affection, which deprived him of the use of the left side. His articulation was now hardly intelligible; he became childish, got gradually weaker, and died December 28, 1796. He was opened twenty-four hours after death. There was a general opacity of the tunica arachnoidea, and a small quantity of water between that membrane and the pia mater: the ventricles were much enlarged and contained a considerable quantity of water, by estimation, four ounces; the consistence of the brain was natural. CASE XVII.