National Geographic : 1924 Jul
Uttcial I'fotograph, U.b.Army Air service THE HIGHEST ALTITUDE PHOTOGRAPH EVER MADE This picture of Dayton, Ohio, was made by Lieutenant John A. Macready and Lieutenant A. W. Stevens inMay, 1924, atanelevation of32,220 feet-more than six miles above the city and 3,000 feet higher than the summit of Mount Everest. The aviators, ofcourse, used oxygen tanks (see illustration, page 86). They encountered terrific cold, the thermometer registering 62/2 degrees below zero. Their plane was visible from the ground for two-thirds of the maximum elevation; after that, its course was indicated for a while by a streak ofvapor, like acomet, but forthelast 3,000 or 4,000 feet it was invisible and its motor could not be heard.