Dec 22, 2013
Diaphragm meter and exerciser (via google patents)
Who knew Respiratory Muscle Strength Devices had such a long history? This patent was filed in 1900 by John E Ruebsam, who had this to say:
It is the object of my invention to provide a simple but efficient apparatus for testing the strength of the diaphragm and also for use therapeutically in exercising it, to the end `the movements of the carriage to and fro.