John Haven Emerson (February 5, 1906 – February 4, 1997) was an American inventor of biomedical devices, specializing in respiratory equipment. He is perhaps best remembered for his work in improving the iron lung. Early life Emerson was born in 1906 in New York City, the son of Dr. Haven Emerson, Health Commissioner of New York City, and Grace Parrish Emerson, the sister of Maxfield Parrish. He was named for his paternal grandfather (1840–1913), who was also a medical doctor. At the age of 22, he bought a rudimentary machine shop from the estate of a local inventor. He moved the equipment to a small warehouse in Harvard Square, in Cambridge, Massachusetts, where he built research apparatus for professors and researchers of Boston-area medical schools, and produced many inventions over the following years. In 1928, he designed a Barcroft-Warburg apparatus for tissue respiration studies. In 1930, he designed a new type of micromanipulator which was valuable in early physiology studies and later saw use in assembly of electronic components. In 1931, Emerson developed an oxygen tent which incorporated an improved cooling system. Work on the iron lung Emerson's father encouraged him to work on an artificial respirator after noticing the beginning of a polio epidemic. Emerson thus began his work on the iron lung in the early 1930s, improving the design of the Drinker lung. Completed in July 1931, Emerson's lung was quieter, lighter, more efficient, and cheaper. With a $1000 price tag, it sold for less than half the price of Drinker's make. Drinker threatened legal action against Emerson, and later filed a lawsuit which backfired. Drinker not only lost the suit, his patents were declared invalid. Emerson's new design replaced blowers and valves with a flexible diaphragm in a dual layer. This acted as a failsafe: if one layer was torn, the second would continue operation. He also made improvements to the chamber. The first example of this design, nicknamed "Old Number One", is currently on display at the Smithsonian Institution in Washington, DC. Emerson continued to make improvements to the iron lung, adding a quick opening and closing function, an improved pressure gauge, and emergency hand operation. His final improvement was the addition of a transparent positive pressure dome, allowing ventilation when the chamber was opened to care for the patient. Later inventions In the mid-1940s, following a suggestion of Dr. Alvin Barach, Emerson perfected the Thunberg