Hull — On the Effect of Continental Land on Level of Ocean. 655 



America, and of the Bocky Mountains of Mexico, in the northern 

 continent, it may be assumed that the ocean surface reaches a 

 higher level along these portions of the coast than elsewhere. 



The general result of our inquiries seems to be, that the form of 

 a geodetic section of the earth, taken parallel to the equator, and 

 at successive intervals both to the north and south of that line, 

 would give curves of ever-varying irregularity according to the 

 position of land and water. That there must be a very important 

 variation from the mean ellipsoidal form along the western margin 

 of the two Americas it is impossible to doubt. Bulgings to a 

 smaller extent may be inferred along the coast-lines. It is prob- 

 able that these equalize one another over the whole surface of the 

 globe ; and, as compared with the diameter of the globe, they are 

 unimportant. Nevertheless, the effect of the elevation and depres- 

 sion of the ocean surface must have been felt throughout all geolo- 

 gical time. The effect of the uprising of mountain chains, or the 

 submersion of lands, in altering the ocean level, becomes an impor- 

 tant element in the discussion of questions connected with the 

 distribution of land and sea both in the present and in past geologic 

 periods. 



I propose to continue the discussion of this subject on a future 

 occasion, the present Paper being only of a preliminary character. 



END OF VOLUME V. 



