GROWTH OF EXPERIMENTAL SCIENCE 177 



experimental work on the same lines, directed to the solution of special 

 phases of the complex problems presented by the intricate structure of 

 folded mountains. 



Mellard Reid/^ on the other hand, investigated the action of heat, in 

 the development through expansion and flow, in sheets of lead and other 

 metals, of structures analogous to those displayed in many mountain 

 ranges. 



These led up to the more extended and important investigations car- 

 ried out by Bailey Willis.^^ 



In these investigations, employing a machine of the same general type 

 as that used by the earlier experimenters and layers of wax of different 

 degrees of plasticity, moving by tangential thrust and under a vertical 

 load produced by a heavy layers of shot, which consequently adjusted 

 itself to the varying form and 'inclination of the folding surface, Bailey 

 Willis studied the deportment under different conditions of load of a 

 series of thin beds, a succession of thick beds, and of a sequence of thick 

 and thin beds. He ascertained the very important role played by stronger 

 layers in transmitting thrust for long distances and developing competent 

 arches, and also the marked manner in which the whole character of the 

 folding was influenced by initial dips in a stratified series. 



This study served to throw very important light on the mechanism of 

 the development of the type of folding displayed by the Appalachian 

 Mountains. 



A further advance was made in this line of experimental work by 

 Paulcke^^ in 1912. The aim which Paulcke set before him was to repro- 

 duce in his experiments the types of structure displayed by certain speci- 

 fied mountain ranges, and having learned how to reproduce each type at 

 will, to analyze the precise causes which determine the deyelopment of 

 one or other type of structure, as the case may be. He selected for study 

 three types of mountain structure, namely, those of : 



1. The Jura. 



2. The western Swiss Alps. 



3. The eastern Lepontine Alps. 



Employing an apparatus similar in a general way to that used by 

 Bailey Willis, he succeeded eventually in being able to reproduce at will 

 any one of these structures, and ascertained from his experimental work 

 that the development of the differences which characterize these several 



11 The Evolution of Earth Structure. Longmans, Green & Co., London, New York, and 

 Bombay, 1008. 



12 The mechanics of the Appalachian structure. J\ S, Geol. Survey. 1.8th Ann. Report. 

 Washington, 189.8. 



"Das Experiment in der Geologie. Karlsruhe, 1012. 



