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The most serious polio patients suffered respiratory failure, and as early as the 1860s, inventors had experimented with apparatuses for artificial breathing. In 1928, Philip Drinker, and and Dr. Louis Agassiz Shaw, in Boston, first sued the term "iron lung" for their machine that varied pressure to aid polio victims' respiration. John Haven Emerson, who ran a machine shop at Harvard Square making medical and scientific instruments saw Drinker's and Shaw's device and imagined improvements, which he completed three years later. His respirator not only worked better, it sold for less than half price of the original "iron lung." Legal battles followed, but Emerson's designs prevailed commercially as the virus created a growing demand.
What is the main idea of this selection?
What is "iron lung" was created to help polio patients breathe; Emerson took this idea and made it better.