" Spheroidal Theory" of the Interior of the Earth. 139 



and contracting crust grasping with ever-increasing force 

 the internal molten mass, until the tenacity of its materials 

 could no longer resist the tremendous reaction. Then would 

 a disruption ensue, and vast quantities of igneous matter be 

 ejected from the yawning fissures. The lips of the chasms 

 would then re-approach and finally press powerfully against 

 each other, producing the phenomena of anticlinal and 

 synclinal foldings so familiar to the geologist. Again, in 

 the gradually up-heaving force generated by the accelerated 

 diurnal motion of the crust, in consequence of its contrac- 

 tion through refrigeration, is seen the cause of those re- 

 peated risings and subsidences which have been going on in 

 all geological periods, from the most remote down to the 

 present. In the changes so effected in the relative distri- 

 bution of sea and land, we recognise one of the most influen- 

 tial climatic agencies, by means of which the temperature due 

 to the position of a place in latitude is powerfully modified. 

 Connected also with the distribution of sea and land is that of 

 terrestrial magnetism, as is at once apparent from a com- 

 parison of a map of isothermal with one of isodynamical 

 magnetic curves. So closely related, in short, are all the 

 parts of the great system of nature, that a discovery in one 

 department becomes a key to the solution of difficulties in 

 others. Geologists are deeply indebted to the physical 

 sciences for the powerful aid which these have furnished 

 them in their investigations, and the physical sciences have 

 already to a small extent been, and will undoubtedly in a 

 great degree be, benefited by the researches of geologists. 



On the motion of the President, the thanks of the Society 

 were given to Mr Stevenson for his communication. 



II. Remarks on Dr Macadam's " Spheroidal Theory" of the Interior 

 of the Earth, By T. Stretiiill Wright, M.D. 



Dr Wright commenced his paper by an enumeration of 

 various circumstances under which fluids assumed the so- 

 called " spheroidal" state, and explained the meaning of the 



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