As the result of the explorations of the atmosphere made by the institution at Mount Weather there was ready for our fighting air men at the front, immediately on our entry into the World War, a fund of useful information concerning a region that but a short time before was entirely uncharted. The instruments carried by the exploring kites and balloons had keen scientific eyes and they recorded on clock-timed cylinders what they saw. Thus did the air pilot know much about the direction and the force of the wind that he would encounter as he rose, the altitude where he would pass above clouds, the degree of cold that he would encounter, etc. He was told that the temperature would fall about one degree for each three hundred feet of his ascent until he reached the top of the storm stratum at six or seven miles, and that if he could reach that altitude he would observe a most wonderful phenomenon: the temperature no longer would fall with gain in altitude; he would enter a cold but an equally heated stratum, without finding any temperatures lower than were encountered upon entering the region, which is always about seventy degrees below zero. If the aërial explorer could stop his ship and keep it at an altitude of about one and one half miles for twenty-four hours he would be startled to find that the coolest time of the period was during the daytime, not during the night, as he had expected to find it. In the future the traveler in the upper reaches of the atmosphere will carry oxygen and make the kind of air that he wishes to breathe, and he will properly protect himself against the cold of his new world, which he will find deficient in dust motes and doubtless entirely wanting in the bacteria of putrefaction and of disease. There will be no clouds to obscure his vision; no rain or snow. He will not often ascend above the region where there are not some dust motes to scatter and diffuse a part of the solar rays and give him at least a partial illumination.