132 Stevenson Macadam on a new Theory of the 



space, and the water in the splieroidal state ; in the globe 

 there are the hot nucleus, the space, and the crust, the inner 

 side of which is in the spheroidal state. 



The crust of the globe, as thus circumstanced, will be in- 

 fluenced by two great forces, viz. : — gravitation and spheroidal 

 repulsion ; the former tending to draw the crust towards 

 the central nucleus, the latter repelling it from it. The crust 

 will, therefore, have assumed the position where the equili- 

 brium of the two forces is established, 



I do not enter at present into the consideration of the 

 relative dimensions of the several portions of the globe, but, 

 considering the rapid increase in temperature from the sur- 

 face of the crust towards the interior, it is not likely that the 

 crust will exceed twenty-five miles in thickness. The inner- 

 most layers of the crust will possess a high temperature 

 which will gradually decrease towards the surface of the 

 earth. 



There is one important feature which all bodies in the 

 spheroidal state present, and which I wish to bring promi- 

 nently forward. I refer to the remarkable property of total 

 reflection of the heat incident upon them. The eff^ect of this 

 property must be to make the inner surface of the crust of 

 the globe (which, it will be remembered, is in the spheroidal 

 state) equivalent in every direction to an immense concave 

 mirror, whose temperature will be very slightly aff^ected by 

 the heat which falls upon it. Such a condition of matters is 

 manifestly compatible with the presence of a much higher 

 temperature at the central nucleus than at the inner surface 

 of the crust, and necessitates a much slower cooling of that 

 crust, and consequently of the nucleus which it robs of heat, 

 than would be the case if the power to reflect heat were not 

 characteristic of the spheroidal condition of matter. And 

 seeing that at a certain, though varying, distance from the 

 surface of the earth, there is an invariable temperature 

 in every latitude, the spheroidal condition of the inner sur- 

 face of the crust must be considered permanent, so long as 

 our present cosmical arrangements continue unchanged ; for 

 as the crust has long ceased to vary in temperature, except 

 within a small distance from the surface, there is no force 



