Geology and Mineralogy. 415 



map of Europe and Great Britain, folded and on cloth, makes a 

 frontispiece to the volume and gives great value to the work. 

 The map is by Wm. Topley, F.G.S., and J. G. Goodchild, 

 F.G.S. It is the only map of the kind in any treatise on geology 

 in the English language. 



2. On the lev el-of -no-strain and mountain making. — The me 1 

 moir by Mr. Davison and Prof. Darwin on the contraction-theory 

 of mountain-making was noticed in the last number of this 

 Journal. The same subject has been further discussed by the Rev. 

 O. Fisher and Mr. T. Mellard Reacle (Phil. Mag. for January and 

 March.) All of these authors agree in the existence of the level- 

 of-no-strain in the earth, first announced by Mr. Reade, and their 

 estimates of its depth do not vary very widely, all agreeing that 

 it must be within a few miles (2 to 5) of the surface. As regards 

 the amount of crumpling of strata on this basis Mr. Darwin (as 

 noted before) makes it small and yet not entirely insignificant 

 (228,000 sq. miles in 10 million years). Mr. Fisher's conclusions 

 upon the supposition of a temperature of solidification of re- 

 spectively 7000° and 4000° are contained in the following table : 



Temperature of solidification. 7000° 4000° 



Depth of level of greatest cooling 54 miles 31 miles 



Depth of level of no strain 2 miles -l 7 miles 



Temperature of level of no strain 358° F. 124° F. 



Mean height of elevations 19 feet 2 feet 



Total contraction of radius 6 miles 2 miles 



Mr. Reade discusses some of the geological consequences of the 

 level-of-no-strain and concludes that it is "plain to demonstration 

 that the lateral pressure that forced up the mountains could not 

 reside in a shell of compression only 5 miles thick having a zero 

 strain in the under side." 



3. Geology of Rhode Island ; Franklin Society Report. 

 130 pp., 8vo., 1887. Providence, R. I. — This report is largely 

 bibliographic, but is very full in notes that review well what is 

 known on the geology of the State and show who have been the 

 observers. They also make it apparent that no thorough study 

 of the geology of the State has been undertaken. The State con- 

 tains the coal formation among metamorphic rocks, and this 

 alone makes it one of the three or four best centres to start from 

 for the study of New England geology. 



4. Annual Report for 1886 of the Geological Survey of 

 Pennsylvania. 8vo. — This part of ' the Repoi't of 1886 contains 

 Part II, on the Oil and Gas Region, by J. F. Carll ; a chapter on 

 the Chemical composition of Natural Gas, by F. C, Phillips, and 

 a Bibliography of Petroleum. 



5. Annuaire Geologique universel, Revue de Geologie et 

 Pal'eontologie ; dirigee par Dr. L. Carez and H. Douville, avec 

 le concours de nombreux Geologues Francais et etrangers ; pub- 

 lie par Le. Dr. Dagincourt. Tome III. Paris, 1887. — The former 

 volumes of this Annual contained, besides lists and abstracts of 

 geological papers of the year, a catalogue of geologists of differ- 

 ent countries, with their places of residence. The present is con- 



