"Recent data on intercostal muscle function, largely electromyographic, tend to confirm the ideas of Hamberger, who, in 1748 (recte 1727), proposed a theory of intercostals muscle action upon the rib cage. Hamberger's scheme was based upon a consideration of the ribs as levers and the vertebral column and sternum as fulcra, and of the directions in which the internal and external intercostal muscle fibers ran. He proposed that the external intercostals were inspiratory and that the internal intercostals were expiratory, except in the parasternal regions where the internal intercostals (there are no other intercostal muscles) are inspiratory. Careful selective electromyographic studies in both animals and man (using small bipolar needle electrodes) by Draper et al, Taylor et al, and Sears et al have amply confirmed Hamberger's ideas" (John T. Sharp., et al., "Respiratory Muscle Function and the Use of Respiratory Muscle Electromyography in the Evaluation of Respiratory Regulation", Chest, 70 , 150).
Digital facsimile of second edition, Jena, 1737, from Google Books at this link.
(Prior editions of this bibliography incorrectly cited the third edition of 1748 for this discovery.)