Annual report of the Royal Humane Society, for the Recovery of Persons Apparently Drowned. 1812.

  • Royal Humane Society (London, England)
Date:
1812
Catalogue details

Licence: Public Domain Mark

Credit: Annual report of the Royal Humane Society, for the Recovery of Persons Apparently Drowned. 1812. Source: Wellcome Collection.

    18/170 (page 8)
    soon as this dilation commences, a sort of vacuum must be formed, between the sides of the thorax and lungs. A current of air, therefore, immediately flows through the wind-pipe into the air-cells of the lungs, and gradually distends these organs, in proportion as the cavity con¬ taining them is increased. This constitutes inspiration. After previous enlargement, the cavity of the thorax may be diminished by the pressure of the abdominal viscera, the elasticity of the parts with which the ribs are connected, and the muscles which pull these bones . downwards, exactly to its natural capacity, or even con¬ siderably below it. When the diminution commences, the lungs are compressed ; and the air, being thus forced out of their cells, escapes by the trachea and mouth. This constitutes expiration. The quantity of air which on an average is expelled by an extreme ex¬ piration, after a previous extreme inspiration, is about 260 cubic inches. We cannot, however, by any mus¬ cular effort whatever, reduce the dimensions of the chest so far as to empty the lungs entirely of their contents. After an extreme expiration, they still retain, on an average, about 40 cubic inches. “ These two processes, of inspiration and expiration, generally alternate with each other, while the body is at rest, about twenty times in a minute. If, therefore, forty cubic inches be adopted, as the average bulk of air inhaled and exhaled, it will result, that a full grown person respires 48,000 cubic inches in an hour, 1,152,000 cubic inches in the course of a day ; a quantity equal to , about 79 hogsheads.” From this view of the phenomena of inspiration and expiration, it may be inferred, that in cases of emer¬ gency