INDIAN OCEAN.--In this ocean the greatest depths appear to exist to the north and west of the Australian continent, where there are more than 3,000 fathoms in a number of widely separated spots, indicating a depressed area of considerable extent. In the most southerly part of the Indian Ocean, or rather in the _Antarctic region_, the Challenger obtained, in 1874, a maximum depth of 1,673 fathoms, in latitude 65° 42' S., longitude 79° 49' E. ARCTIC OCEAN.--The greatest depth was sounded by the Sofia in 1868, 2,650 fathoms, in latitude 78° 05' N., longitude 2° 30' W. In the minor seas the maximum depths so far as ascertained are: Caribbean Sea 3,452 fms., south of Great Cayman. Gulf of Mexico 2,119 " (Sigsbee Deep). Mediterranean 2,170 " North Sea 375 " Baltic 178 " China Sea 2,100 " Coral Sea 2,650 " Sulu Sea 2,550 " Celebes Sea 2,600 " Banda Sea 2,800 " January, 1889. REPORT--GEOGRAPHY OF THE AIR. BY A. W. GREELY. In presenting to the National Geographic Society a summary of geographic advance as regards the domain of the air, the Vice-president finds a task somewhat difficult. The traveler passes from the east to the west coast of Africa, and his very efforts to struggle across that great continent, impress in his memory an abiding picture of the physical features of the country over which he has passed, and of the distribution of plants and animal life. So, too, a vessel sails from one coast to another, casting here and there a sounding lead, from which measurements it is possible to give quite a definite idea of the relief features of the bottom of the sea. Small as are the traces which serve to indicate the character of the sea bottom, yet they are infinitely greater than those which enable us to give a description of the air. Atmospheric disturbances are so vast, and their action is so rapid, that it requires the attentive care of thousands of observers before one can well hope to draw the roughest figure of a passing storm. To note changes in the force and direction of the wind, to note the depth of the rain, the increase and decrease of temperature and the varying changes of aqueous vapor, either in visible or invisible form, requires millions of careful, systematic observations, and then when these are made, the task of collating, elaborating and discussing them seems almost too great for any man. Fortunately the value of meteorological work has impressed itself not only upon governments, which have assisted liberally by appropriations and organization, but yet more upon the isolated observer, thousands of whom over the face of the earth give of their time and labor, and add their mite to the wealth of universal knowledge.