In the February number of theJournalI described a double stethoscope which I have employed during the past three years for class demonstration of physical diagnosis in Rush College. In a later number of theJournal, Dr. H. A. Hare, of Philadelphia, described a multiplex stethoscope upon the same principle, but using tubes long enough to allow some sixteen individuals to listen at once. The double stethoscope makes possible the accurate demonstration of sounds which both instructor and student hear together—a multiplex stethoscope, if properly constructed, not only has this in view, but more, in the saving of time. I have devised a multiplex stethoscope as represented in the accompanying cut, kindly furnished by Sharp & Smith, of this city. I first experimented with long tubes. A semicircle of twelve chairs, placed side by side, will bring a patient at a radial distance of about five feet; while the