Science . times we deduce the values ofgravity at the various places, and it wasshown many years ago by Stokes that theshape of the geoid can be inferred from thevariation of gravity over the surface. The question to which I wish to inviteyour attention is a different one. If theocean could be dried up, the earth wouldstill have a shape. What shape would itbe? Why should the earth have that shaperather than some other ^ In order to de-scribe the shape we may imagine that wetry to make a model of it. If we couldbegin with a model of the geoid we shouldhave to attach additional material over the
Science . times we deduce the values ofgravity at the various places, and it wasshown many years ago by Stokes that theshape of the geoid can be inferred from thevariation of gravity over the surface. The question to which I wish to inviteyour attention is a different one. If theocean could be dried up, the earth wouldstill have a shape. What shape would itbe? Why should the earth have that shaperather than some other ^ In order to de-scribe the shape we may imagine that wetry to make a model of it. If we couldbegin with a model of the geoid we shouldhave to attach additional material over theparts representing land and to removesome material over the parts representingsea. Our model would have to be as bigas a battleship if the elevations and depres-sions were to be as much as three or fourinches. In thinking out the constructionof such a model we could not fail to be im-pressed by certain general features of thedistribution of continent and ocean, and wemay examine a map to discover such fea-. tures. Fig. 1 is a rough map of the worlddrawn in such a way that to every degreeof latitude or of longitude there cor-responds the same distance on the very prominent features have often been remarked: the tapering of Americaand Africa towards the south, the dispro-portion between the land areas of thenorthern and southern hemispheres, theexcess of the oceanic area above the conti-nental area, which occupies but litttle morethan one quarter of the surface; the wideextent of the Pacific Ocean, which with theadjoining parts of the Southern Oceancovers nearly two fifths of the prominent feature is the antipodalposition of continent and ocean. SouthAmerica south of an irregular line whichruns from a point near Lake Titicaca toBuenos Ayres is antipodal to a portion ofAsia which lies in an irregular trianglewith corners near Bangkok, Kiaochau andLake Baikal; but no other considerableparts of the continental system have con-tinental antipodes. The Antar
Size: 2115px × 1182px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjects, booksubjectscience
