In 1869 Professor Cleveland Abbe published a weather bulletin at Cincinnati, based upon simultaneous observations secured by telegraph from about thirty stations. He was the first scientific assistant to General Meyer and remained continuously with the service until his death in 1919. Colonel (afterward Brigadier-General) H. H. C. Dunwoody, U. S. A., served twenty-seven years as an expert forecaster or as the assistant chief of the Weather Bureau. General A. W. Greely, of Arctic fame, the last of the military chiefs, succeeded Brigadier-General William B. Hazen on the death of the latter. Professor Mark W. Harrington was the first chief of the new civil Weather Bureau; he served but four years and was succeeded by Professor Willis L. Moore, who remained chief for eighteen years, serving two years under President Cleveland, who appointed him, and during the entire administrations of McKinley, Roosevelt, and Taft, and was removed by Woodrow Wilson immediately on taking office. Professor Moore claims the honor of having been the first presidential appointee to incur the displeasure and receive the public condemnation of Woodrow Wilson. The present chief is Professor Charles F. Marvin, who for many years served as an assistant to Professor Moore. INDEX INDEX Abbe, Cleveland, 298; publishes weather bulletin, 305; his long service in the Weather Bureau, 305 Absolute humidity, 39 Absolute zero, 62 Aërial ocean, the air a great, 7 Aëroplane, importance of developing the, 27 Africa, and monsoon winds, 107; hottest and coldest places in, 279 Agricultural interests, benefit of Weather Bureau service to, 301, 302 Air, great ocean of, around the earth, 7; condition of, at various levels, 7-17; liquid, 9; blue tint of, 10; thinness of stratum of, that sustains life, 14; elasticity and density of, 14; pressure of, 15; weight of, 15; everything evolved from, 15-17; effect of cold wave on the, 36, 37; explorations of the, 18-28; circulation of the, 55; increasing pressure increases temperature of, 61; difference between weight and pressure of, 77; course of a current of, 99; earth warmer than, next above, 180; cools with ascent and heats with descent, 184; height of freezing cold in free, 185; daily range of temperature in free, 185, 186; movement of, in valleys, 204; mountains and movement of, 205; proper temperature and humidity of, in habitations, 217; water vapor in, at various temperatures, 284; retards falling raindrops, 285; and the formation of cloud, 287, 288 Air travel, Major Blair on, 27; Lieut. Col. Henry on, 28 Aitken, Robert Grant, method of counting dust motes, 44, 45