I must here refer to another means of alleviation, concerning which I can not bear the witness of personal experience, but which has been highly recommended to me. Even this brief sketch of treatment would be imperfect without at least a mention of it, and if it possesses all the value claimed for it by persons of judgment who have reported it to me, it will form an indispensable part of our apparatus on Lord's Island. This is an air-tight iron box of strongly-riveted boiler plates, with a bottom and top fifteen feet square and sides ten feet high; thick plate-glass bull's-eyes in each side sufficiently large to light the interior as clearly as an ordinary room; and a cast-iron door, six feet in height, shutting with a rubber-lined flange, so that all its joints are as air-tight as the rest of the box. Inside of the box, in the centre, stands a table, suitable for reading, writing, draughts, cards, chess, or games of any similiar kind, with comfortable chairs arranged around it corresponding in number to the people who for an hour or two could comfortably occupy the room. In one side of the box is a circular aperture connecting with an iron tube, which in its turn is joined to a powerful condensing air-pump outside, and on the other side is a pressure gauge with its index inside the box. Sufferers from severe neuralgic pain being admitted, the air-tight door is shut; they seat themselves, and the condensing pump is set in motion by an engine until the gauge within indicates a pressure of any amount desired. I am told that the severest cases of neuralgia have found instantaneous and thorough relief by the addition of six or eight atmospheres to the usual pressure of air upon the surface of the body. There is no reason why the condensation might not be continued to twenty or more, the increased density causing no uneasiness to those within the box, the same equilibrium between internal and outward pressure that exists everywhere in the air being maintained here. Persons who have made trial of this apparatus speak of the cessation of their pain as something magical; say they can feel it leaving them with every stroke of the pump; and although as yet we may not be able to offer a scientific explanation of the relief afforded, we can not fail to see its applicability to the case of the reforming opium-eater. If it does all that is claimed for it, it probably acts both mechanically and chemically--the pressure, even though imperceptible from its even distribution, affecting the body like the shampooing, kneading action of an attendant's hand, and the vastly increased volume of oxygen which it affords to the lungs and pores accelerating those processes of vital decomposition by which the causes of many a pain, but especially that of our patient, are to be removed.