138 Proceedings of the Royal Physical Society. 
which, being greater than that of the immediately subjacent 
mass, the crust so formed would necessarily sink. In like 
manner it may be shown that all crusts under a certain 
thickness would sink, whilst all above such a thickness would 
float. It thus appears that the thin crusts originally formed 
would sink and undergo total or partial re-fusion until a 
certain thickness of solid matter was attained. By this 
arrangement the refrigeration of the superficial parts of our 
globe would proceed with far greater rapidity than if the 
thin crust originally formed had maintained its position, as 
in this case the heat from the interior could only have 
reached the surface by the slow process of conduction 
through a solid mass of very low conducting powers. In 
this, then, there also appears evidence of design in hastening 
the progress of our globe through its uninhabitable stages, 
that it might be the sooner fitted for the habitation and 
enjoyment of the sentient beings for whose use it was 
destined. 
The deductions contained in the preceding paragraphs 
are humbly -presented to the consideration of all who are 
interested in the study of geological phj^sics. Though some 
of the assumptions founded upon may perhaps be called in 
question, and although in the calculations many corrective 
elements have not been taken into account, it is hoped that 
at least glimpses of some important truths have been ob- 
tained, sufficient to attract the attention of more competent 
investigators. The astonishing progress which the physical 
sciences have made within the last half century encourages 
us to hope that the time is not far distant when sufficient 
data shall be obtained to enable us to work out the solution 
of many of the most important problems connected with 
geological dynamics. Even now, in studying the phenomena 
resulting from the refrigeration of our globe, we obtain a 
clue to the nature and modus operandi of some of the causes 
by which the varied configurations of the earths surface 
have, in the present as well as in the past geological epochs, 
been produced. For example, in the fissures opened in 
consequence of refrigeration, we see at once the origin of 
mountain chains. We can imagine the gradually cooling 
