The fatal effects of confined air in a small and crowded room, were fully exemplified in the year 1742, when twenty persons were crammed in a part of St. Martin’s round-house called the _hole_, during the night, several of whom died; the surgeons on that occasion gave it as their opinion, that when the doors and windows were shut, the place could not support twenty persons for three hours without danger of their lives. A trial took place at the Old Bailey in consequence; but we have not been more successful than _Dr. Gordon Smith_ in our search for its report. The medical jurist would be called upon, on such an occasion, for his opinion as to the nature of the deteriorated air, the causes of its accumulation, and whether it was adequate to the production of the alleged effects; and possibly, whether the fatal consequences might not have been averted by judicious caution, or active exertion. The most awful exemplification of the fatal effects of confined air is, however, recorded in the interesting narrative of what happened to the English in the _black hole_ at Calcutta; and which we shall briefly relate in this place; as it involves some physiological phenomena to which we shall hereafter have occasion to refer. It was in the month of June, 1756, that the Viceroy of Bengal laid siege to Fort William, the English factory at Calcutta. _Mr. Holwell_, assisted by the factors and the garrison, defended this post with extreme bravery; but was at length obliged to surrender. There were at this time remaining in the fort, an hundred and forty-five men and one woman. The whole of this unfortunate company, many of whom were wounded, and several very dangerously, were shut up the same night in a small prison only eighteen feet square. This prison, which is now better known in England by the name of the _black hole_, was enclosed by strong walls, and had only two small windows at one end, secured by iron grates. In this confined situation, which allowed only a space of about eighteen square inches to each individual, the heat and want of fresh air soon excited the most horrible effects; the prisoners, in a state of despair, began by attempting to force open the door, but in this they were unsuccessful. Mr. _Holwell_, who was placed near one of the windows, was more at his ease than the rest, and was consequently more cool and tranquil; and he recommended his companions to be quiet and orderly, and not to exhaust their strength by useless efforts. This advice produced some little calm, interrupted, however, by the groans of the wounded and the dying. The heat increased every moment. Mr. _Holwell_ recommended them to strip off their cloaths, as a means of acquiring more space; this was accordingly done, but with no great relief; they attempted to improve this by fanning the air with their hats, but even this was too painful a task for men who were worn out by the fatigue of the siege, and the heat of this dungeon. Another of the