Willis Carrier presented his Rational Psychrometric Formulae on December 8, 1911 at the annual meeting of the American Society of Mechanical Engineers. It provided the first mathematical method of psychrometric calculation—precisely relating temperature and humidity--and soon became the authoritative standard. Along with this paper, Carrier also presented Air Conditioning Apparatus—Principles Governing Its Application and Operation, which was a comprehensive discussion of humidifying and dehumidifying apparatus and automatic controls.
His invitation to present at the meeting was recognition that air conditioning had become an established industry and new branch of engineering. Carrier’s psychrometric chart would be reproduced in college textbooks, taught in engineering schools, and translated into foreign languages. At 35 years old, Willis Carrier had become internationally recognized as the Father of Air Conditioning.