a co-operative paper prepared by the American Gas Association, represented by H. O. Andrew, A. M. Apmann (chairman), C. W. Berghorn (secretary) [and others] ; American Society of Mechanical Engineers, represented by H. W. Brooks [and] George A. Orrok ; American Society of Heating and Ventilating Engineers, represented by G. C. Carnahan [and] N. T. Sellman