Breathing.–Respiration, or the act of breathing, consists of thealternate inspiration and expiration of air to and from the lungs; in the process of which the lungs themselves are almost passive managements, since their contraction expansion takes place by means of the muscles which surround the chest. The diaphragm or midriff, which, when at rest in the lungs empty, forms a beautiful dome to the abdominal cavity, becomes depressed during the inspiratory process, and presses the walls of the abdomen outward. At the same time the ribs become elevated, thus increasing the size of the chest. Thereupon the elastic lungs expand to occupy the entire space, whilst the current of air, in obedience to a well known physical law, rushes down the windpipe and enters the numerous air cells, the result of which is inspiration. In expiration the reverse of this takes place. We bend forward, draw the abdominal walls inward, press the diaphragm upward, whilst the ribs are pulled downward. All these acts simultaneously performed decrease the size of the chest, and force or expel the air from the lungs.

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This is another one of those segments where there are excessive number of comments, however the writing is actually fairly descriptive of the process. Today the commas are a distraction but the writing is pretty good here. It is not extremely technical nor does it get into many of the finer details of the inner workings of the lungs, but from the perspective of a person describing the breeding action of the lungs as observed from the movement of the chest this is pretty good.

Make no mistake at this point in time scientists had often studied the lungs of animals and sometimes even people in action without the obstruction of a skin or the chest cavity. Scientists almost two hundred years earlier had performed what would be considered today fairly brutal experiments on animals and dogs in particular to gain a working knowledge of the organs. Battle field physicians also received a great deal of experience in war time and this book series actually was first published during the time of the American Civil War.