from Spitzbergen. Depths from 100 to 1,000 fathoms may be considered as shallow in comparison with the prevailing depths from 2,000 to 3,000 fathoms of the principal oceanic basins, and sufficient to establish a connection between islands and continents, the more so as we generally find one or more islands occupying the intervening space, thus betraying the common link between them. The result of this examination is that all the larger land masses compose an area of elevation which, after nearly completing the circuit of the world in the latitude of the Arctic Circle, subdivides itself into two parts, an eastern and a western one--the former embracing Europe, Africa, Asia, and Australia, the latter North and South America. In a similar manner, the different oceans combine into an area of depression which, after making the circuit of the world along the parallel of lat. 60° S. under the name of the Southern Ocean, divides itself into three large basins, respectively designated as the Pacific, the Atlantic, and the Indian Oceans. Thus the two elements, land and water, starting from opposite hemispheres, extend their arms across the equator, holding each other in close embrace, like two champions wrestling for the mastery of the world. A comparison of the deep-sea soundings obtained up to the present date shows that, if we omit the seas situated beyond the parallels of lat. 60° N. and lat. 60° S.--no depths exceeding 2,000 fathoms having as yet been ascertained beyond these latitudes--the average depth of the ocean between these parallels may be estimated at about 2,500 fathoms, or more roughly at three English miles, and the average depth of all seas on the surface of the globe at probably two miles. Contrary to the ideas formerly entertained of the enormous depth of the ocean, the soundings of H.M.S. _Challenger_, S.M.S. _Gazelle_, and of the U.S.S. _Tuscarora_ and _Gettysburg_, indicate that depths of five miles, or even 4,000 fathoms, are but seldom met with, and are as exceptional as heights of the same amount on land. One of the greatest depths ascertained in the Atlantic was found by H.M.S. _Challenger_, about eighty miles north of the island of St. Thomas in the West Indies. It is 3,875 fathoms, or about four and a half miles. In May, 1876, the _Gettysburg_ found 3,593 fathoms only eleven miles south of the _Challenger_ sounding. A depth of 3,370 fathoms obtained by the American ship shows that the deepest area in the Atlantic is placed to the northward of the Virgin Islands, and extends over 400 miles along the meridian of 65° W. The greatest depth observed in the Indian Ocean was discovered by the _Gazelle_ in May, 1875. Two soundings of 3,020 and 3,010 fathoms were taken in the eastern extremity of this ocean between the northwest coast of Australia and the line of islands extending from Java to Timor.