In 1862 the English meteorologist Glashier ascended in a balloon to about the same height as that attained by Major R. W. Schroeder, U. S. A., who achieved a more difficult feat when he flew in an aëroplane to over 36,000 feet. And at Dayton, Ohio, celebrated as the home of the Wright brothers, on September 28, 1921, Lieutenant John A. Macready, U. S. A., reached the unprecedented height of 40,800 feet. These are the extreme altitudes to which human beings ever have attained, but they are only the beginning of explorations into a vast and largely unknown and extremely cold region,—one in which darkness increases with elevation until at the outer limits of the atmosphere no illumination whatever exists. The high eastward wind and 69° below zero encountered by Schroeder are conditions that already had been revealed by the work done at the research station of the Weather Bureau, at Mount Weather, Virginia, and at other stations in this country and in Europe, by the sending up of instruments unaccompanied by observers. Under the direction of the writer the Weather Bureau liberated numerous small hydrogen gas balloons in the Rocky Mountain region, to which were attached automatic instruments registering the temperature, pressure, and the hygrometric conditions. As they came eastward in the atmospheric drift that always prevails above the storms in the middle latitudes they attained to great altitudes, one balloon reaching 19.1 miles, the greatest altitude ever reached at that time by the appliances of man. Ultimately the balloons would explode as they expanded under the influence of decreasing air pressure and the case of instruments would descend slowly under a parachute designed to open at the right moment. The barometer traced a line on a paper cylinder revolving by clock works, as did the thermometer. The thermogram gave the temperature that corresponded with the varying elevation shown by the tracing of the barogram. In 1898, twelve hundred observations were made with kites by the observers of the Weather Bureau at seventeen stations selected by the writer, during the six warm months from May to October. It was surprising to find the temperature often losing as much as fifteen degrees with the first thousand feet ascent during middays of extremely hot periods. The average decrease in temperature per thousand feet elevation for all stations for all times, and at all elevations up to 5280, was 4°. For over five years kites were used nearly every day in the year at Mount Weather to carry instruments aloft to heights ranging from two to four and one half miles, and at times to keep the apparatus up during all hours of the day, so that a comparison could be made of the difference between day and night temperatures. There is but little difference between midday and midnight at only a few thousand feet above the earth.