GEOLOGY. 277 



into eight others by means of line of accidents of minor importance, 

 so as to make in all forty-eight irregular triangles, a form of the dia- 

 mond. At the intersections, M. de Hauslab observes that there are nodes 

 of dykes, and along the lines or near them, all the mountains of the 

 globe occur. The author gives an extended illustration of his subject 

 and afterwards considers the particular history of the configuration of 

 the earth's surface in accordance with his hypothesis. 



M. Boue who adopts similar views adds as a note, that we should 

 remember in this connection that the metals crystallize either in the 

 tesserel or rhombohedral system, and that native iron, the most com- 

 mon constituent of meteorities, is octahedral in its crystals. 



OX THE STABILITY OF THE EARTH'S AXIS OF ROTATION. 



THE following is a communication read before the Royal Society, 

 by Henry Hennessy, Feb., 1852. 



* The author refers to a communication to the Geological Society, by 

 Sir John Lubbuck, in which he appeals in support of the possibility 

 of a change in the earth's axis, to the influence of two disturbing 

 causes, which appear to have almost entirely escaped the notice of 

 Laplace and Poisson, in their investigations on the stability of the 

 earth's axis of rotation; 1. The netessary displacement of the 

 earth's interior strata, arising from chemical and physical actions 

 during the process of solidification. 2. The friction of the resisting 

 medium in which the earth is supposed to move. With reference to 

 the first of these disturbing causes, the author states, that he has been 

 led to conclusions which may assist in clearing up the question. From 

 an inquiry into the process of the earth's solidification, which appears 

 to him most in accordance with mechanical and physical laws, he has 

 deduced results respecting the earth's structure which throws some 

 light on the changes which may take place in the relation which is 

 capable of being expressed by means of a function which depends on 

 the arrangement of the earth's interior strata. He then states that he 

 has found strong confirmation of his peculiar views respecting the 

 theory of the earth's figure in the experiments of Bischof of Bonn on 

 the contraction of granite and other rocks or passing from the fluid 

 to the solid crystalline state. From the results of these experiments, 

 he has been led to assign a new form to the function expressing the 

 relation of the earths' principal moments of inertia. Referring to his 

 paper for the mathematical processes by which he has arrived at this 

 result, he states that from the theory he has ventured to adopt, it 

 follows, that as solidification advances, the strata of equal pressure in 

 the fluid spheroidal nucleus of the earth, acquires increased elliptic- 

 ity, and each stratum of equal density, successively added to the 

 inner surface of the solid crust, is more oblate than the solid strata 

 previously formed. 



From these considerations alone, he remarks, it is evident that the 

 difference between the greatest and least moment of inertia of the 

 earth, would progressively increase during the process of solidification. 



