To the Editor.
—The article by Nicholas et al1 entitled "Is Syncope Related to Moderate Altitude Exposure?" is exciting; however, extensive research on moderate- and high-altitude syncope was performed about 80 years ago, and JAMA published an article about the physiology of much of this in 1918.2In 1912, investigations into the stress effects of altitude were made by the "Anglo-American Expedition to Pike's Peak," involving a remarkable quartet of physiologists—Douglas, Haldane, Henderson, and Schneider. These basic studies were published in England as a 146-page article in 1913.3 Schneider, at the University of Colorado, acted as the host of this expedition.By 1915, Yandel Henderson at Yale University had developed his rather hazardous rebreathing apparatus. Breathing for 10 to 15 minutes into this spirometer (when it was set to hold 55 L of confined air) accurately produced the anoxic syndrome that develops when oxygen thins out (or