i62 REVIEWS 



of seismologic phenomena, that a new volume of five hundred pages by 

 M. Montessus de Ballore, entitled Les ireniblements de terre, has been 

 recently published at Paris. In the preface M. de Lapparent directs atten- 

 tion to the great statistical value of the author's catalogue of earth- 

 quakes, and to the fact that he has brought seismology into its relations 

 with geologic structure. 



J. C. Branner. 



The Linear Force 0} Growing Crystals, and an Interesting Pseudo- 

 Solid. By G. F. Becker and A. L. Day. Proceedings of 

 the Washington Academy of Sciences, Vol. VII (1905), pp. 

 251-300. 



About six months ago a modest paper, filling only five octavo pages, 

 was published by George F. Becker and Arthur L. Day upon the "The 

 Linear Force of Growing Crystals."' The writer has looked in vain 

 for expressions of appreciation of this important piece of work. 



Evidences of the linear force of growing crystals have long been familiar 

 to geologists, but while the process of growth seemed clear enough from 

 field observations, the demonstration of it and its quantitative determination 

 have hitherto been altogether lacking, while the writer's efforts to interest 

 chemists and physicists competent to deal with the problem have failed of 

 success for twenty years. Discussions of the origin of secondary veins 

 usually proceed on the theory of cavities, or of the replacement of one 

 mineral by another. So far as we now recall, not one of the many writers 

 on this much-discussed subject has ventured the suggestion that the grow- 

 ing force of crystals may have thrust apart the rock walls, and thus made 

 room for the veins in the very process of formation. A few geologists 

 have suggested that some such force operated in the formation of veins, 

 but these are so few, and their suggestions have been made with such 

 apparent hesitation, that little or no attention has been paid to them by 

 the more voluminous writers upon ore deposits. 



In 1882 Chamberlin recognized the displacing force of growing crystals 

 of sphalerite, galenite, and pyrite in the ore deposits of southwestern Wis- 

 consin, as indicated by the following quotations from Vol. IV of Geology 

 oj Wisconsin: 



In most instances it is perfectly clear, from the nature of the ore filling, that 

 the separation of the beds took place before the implanting of the ores, 



I Proceedings of the Washington Academy of Sciences, Vol. VII (July, 1905), pp. 

 283-88. 



