E. MINERALOGY AND GEOLOGY. 223 



nearly 0.067; and lie states that the earth's diameter, being 

 at present 7916 British miles, it must, when liquid, have 

 been a globe 8105 miles in diameter, and when at the tem- 

 perature of incipient consolidation, it must have been 7957 

 miles in diameter. The earth, therefore, between its period 

 of liquidity and its present state, has shrunk in diameter by 

 189 miles at the least. Phil. Trans. Roy. Soc, CLXIII., 187. 



THE LINES OF ELEVATION IN THE EARTH'S CRUST. 



Mr. Angus Ross, of Halifax, announces a generalization de- 

 duced by himself with regard to the lines of elevation on the 

 earth's crust, which is well worthy of close criticism and care- 

 ful examination. He claims to have discovered that the va- 

 rious mountain chains, or line of anticlinal elevation, are 

 ranged in parallel lines along certain belts or zones, which 

 girdle the earth, each zone following, approximately, the 

 course of a great circle, and each having for its medial line 

 or axis a line of volcanoes. Of these zones he describes seven. 

 The following description of one may serve as a type of the 

 rest : 



" The Rocky Mountain system has its axial line in the vol- 

 canic belt extending from the Middle Andes, inclusive, across 

 Central America, along the Rocky Mountains, Alaska, the 

 Aleutian Islands, Kamtschatka, the Kurile Islands, Japan Isl- 

 ands, Loo Choo Islands, Philippine Islands, Palawan, and Bor- 

 neo. The islands of Amsterdam and St. Paul, the Kerguelen 

 Islands, the South Sandwich Islands, and South Georgia, seem 

 to indicate the completion of the more southerly jmrt of the 

 great circle." The author describes seven such zones or belts, 

 and argues that their intersections constitute a foci of vol- 

 canic energy. He also maintains that the great mountain 

 chains, in their directions, follow the course of one or other 

 of these zones. 12 A, IX., 380. 



THE FORMATION OF THE EARTH'S CRUST. 



In an inaugural of Dr. Lang there is a theory of the forma- 

 tion of the earth's crust that will be of interest in these days, 

 when Mallet's theories are so ably defended and controverted. 

 According to Lang, as the fluid mass cooled and crystallized 

 or solidified, there occurred immediately a sensible expansion, 

 the specific gravity became a minimum, and the stone Avas 



