REPORT — 1853. 



de Beaumont was the originator, and has been the great advocate of this ex- 

 tension of the theory of parallelism. He extends it, in fact, to the whole sur- 

 face of the eai'th, using the term parallelism in a certain modified sense, to 

 render it applicable to lines drawn on a spherical instead of a plain surface. 

 Mis theory asserts that all great lines of dislocation, and therefore all moun- 

 tain chains originating in them, wherever situated, may be grouped into 

 parallel systems, and that all the lines or mountain chains belonging to any 

 one system were produced simultaneously by one great convulsion of the 

 earth's crust. This theory has been advocated by him many years, but he 

 lias recently published his latest views respecting it, and has made an im- 

 portant addition, which may, in fact, be regarded as an independent theory. 

 Each of the parallel systems already mentioned will have its cJiaracteristic 

 direction, to which all the lines of that system are parallel. This new theory 

 asserts that these characteristic directions are not determined, as it were, by 

 accident or chance, but that they have certain relations to each other, so that 

 the respective systems to which they belong are disposed over the earth's 

 surface, according to a distinct symmetrical arrangement. For the details of 

 this curious theory I can only refer to the author's work, or to the analysis 

 which I gave of it last February, in ray address to the Geological Society. 1 

 feel it right, however, to add, that after an attentive examination of the sub- 

 ject, the evidence adduced by M. de Beaumont in support of the last-men- 

 tioned theory has failed to convey conviction to my own mind. With re- 

 ference to the parallelism of contemporaneous lines of elevation, no one, I 

 conceive, will deny the truth of M. de Beaumont's theory in its application 

 to many geological districts of limited extent ; but it will probably be the 

 opinion of most English geologists, that, in attempting to extend it to districts 

 far remote from each other, he has overstepped the bounds of legitimate in- 

 duction from facts with which we are at present acquainted. Every one, 

 however, who studies M. de Beaumont's work, in whatever degree he may be 

 disposed to adopt or reject the theoretical views of that distinguished geolo- 

 gist, will admit the ability and the knowledge which he has brought to bear 

 on the subject, and the advantages which must result from the ample discus- 

 sion which he has given it. 



One favourite subject of speculation in the physical branch of geology has 

 been, at all times since the origin of the science, the state of the interior of 

 our planet, and the source of the high temperature observed at all consider- 

 able depths beneath its surface. The terrestrial temperature at a certain 

 deptii in each locality (about SO feet in our own region) remains constant during 

 the whole year, being sensibly unaffected by the changing temperature of 

 the seasons. The same, of course, holds true at greater depths, but the 

 lower we descend the greater is this invariable temperature, the increase 

 being proportional to the depth, and at the rate of 1° Fahr. for about every 

 60 or 70 feet. Assuming this rate of increase to continue to the depth of 

 .50 miles, we should arrive at a temperature about twice as great as that 

 necessary to fuse iron, and sufficient, it is supposed, to reduce nearly the 

 whole mass of the earth's solid crust to a state of fusion. Hence the opinion 

 adopted by many geologists is, that our globe does really consist of a solid 

 shell, not exceeding W or 50 miles in thickness, and an interior fluid nu- 

 cleus, maintained in a state of fusion by the existing remains of the heat to 

 whicli the whole terrestrial mass was originally subjected. It might, at first 

 sight, appear that this enormous mass of molten matter, enclosed in so thin 

 a shell, could scarcely be consistent with the general external condition and 

 temperature of our globe ; but it is quite certain that the real external tem- 



