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One of the meansused for exploring the state of thoracie and other cavities. It consists in a comparative measurement of each side of the chest, by means of a riband extended from the median line of the sternum to the spine. When effusion exists on one side, the measurement is usually greater than on the other. When, on the other hand, a portion of a lung has ceased, for sometime, to exert its respiratory functions, the corresponding side of the chest becomes smaller, in consequence of the contraction of the pleura, retraction of the pulmonary tissue, and grater approximation of the ribs.