OCTOBEE 25, 1907] 



SCIENCE 



539 



of such changes might be the occurrence of 

 gTeat subsidences in the neighborhood of 

 the Crimea, where we found the maximum 

 of the first harmonic. Such subsidences 

 are supposed by geologists to have taken 

 place in rather recent times. Symptoms 

 of the diminution of the inequalities ex- 

 pressed by harmonics of the second degree 

 would be found in the gradual disappear- 

 ance of seas forming part of the great de- 

 pression which was described above as a 

 sort of immense Mediterranean {cf. Fig. 7) 

 in the destruction and inundation of a con- 

 tinent in the northern Atlantic and in a 

 gradual increase of depth of the southern 

 Pacific. The disappearance of seas from a 

 vast region surrounding the present Medi- 

 terranean basin, and containing the Sahara 

 and southern Asia as far east as the Hima- 

 layas, is one of the best ascertained facts 

 in geological history; and the belief in the 

 destruction of a north Atlantic continent 

 is confidently entertained. In parts of the 

 southern Pacific a depression represented 

 by harmonics of the third degree is super- 

 posed upon an elevation represented by 

 harmonics of the second degree, and we 

 should therefore expect to find the depth 

 of the ocean to be increasing gradually in 

 this region. The region in question is that 

 of the coral reefs and coral islands, such 

 as Funafuti, and the result is in accord 

 with Darwin's theory of the formation of 

 coral reefs. So far as the general dis- 

 tribution of the mass within the earth is 

 concerned, the reduction of the inequalities 

 of the first and second degrees would seem 

 to have already proceeded very far ; for we 

 are assured by geodesists that harmonies of 

 the first degree, and those of the second 

 degree which do not represent the effect of 

 the rotation, are far from prominent in the 

 figure of the geoid— much less prominent 

 than we found them to be in the distribu- 

 tion of continent and ocean. We infer 



that the inequalities of the first and second 

 degrees must have been progressively 

 diminished in comparison with those of the 

 third degree. The general result of such 

 changes would be a gradual diminution of 

 the depths and extents of the oceans which 

 correspond with the harmonics of the first 

 and second degrees, and a compensating in- 

 crease in the depths and extents of the 

 oceans which correspond with the harmonic 

 of the third degree. To see the character 

 of the changes which would thus be brought 

 about, we may examine a figure which 

 shows the composite elevations and de- 

 pressions that are represented by harmonics 

 of the first and second degrees, and, sepa- 

 rately, those which are represented by 

 harmonics of the third degree. In Fig. 15 





Fig.15. 



the composite elevations of the first and 

 second degrees are shaded vertically, and 

 the elevations of the third degree are 

 shaded horizontally. The deep parts of 

 the Atlantic that border the coasts every- 

 where from Brazil to Ashanti are regions 

 in which a depression represented by the 

 third harmonic is superposed upon an ele- 

 vation represented by the other two har- 

 monics, and the same is true of the deep 

 parts of the Indian Ocean which border 

 the shores of Africa and Asia from Mada- 

 gascar to Burmah. The deep parts of the 

 Pacific that border the western coast of 

 America from Alaska to Chile are regions 

 in which an elevation represented by the 

 third harmonic is superposed upon a de- 



