139 



Articlk VII. 



Researches an the Elasticity of Bodies ivhich crystallize regie- 

 larly ; by Felix Savart. 



(Read to the Academy of Sciences of Paris, January 26th, 1829.) 

 From the Annates de Chimie et de Physique, vol. xl. p. 5, et seq. 



JtllTHERTO precise notions respecting the intimate structure of bo- 

 dies could be acquired only by two means : first by cleavage, for opake 

 or transparent substances regularly crystallized ; secondly, for transparent 

 substances only, by the modifications which they occasion in the propa- 

 gation of light. 



The first of these means has taught us that crystallized bodies are col- 

 lections of laminae parallel to certain faces of the crystal ; but it has given 

 us no information respecting the force with which these laminae adhere 

 together nor their elastic state. The second, far more powerful than 

 the first, because it renders evident actions depending on the very form 

 of the particles, has given rise to the discovery of phaenomena the exist- 

 ence of which cleavage alone would never have allowed us to suspect. 

 But although these two experimental processes have introduced many 

 new ideas and notions into the science, yet it may be said that the part 

 of physics which treats of the arrangement of the particles of bodies, 

 and the properties resulting from it, as elasticity, hardness, fragility, 

 malleability, &c. is still in its infancy. 



The investigations of Chladni respecting the modes of vibration of 

 laminae of glass or metal, and the researches which I have published on 

 the same subject, especially those which relate to the modes of division 

 of discs of a fibrous substance, such as wood, allow us to suspect that we 

 might acquire by this means new notions respecting the distribution of 

 elasticity in solid bodies; but it was not clearly seen by what process 

 this result might be attained, though the road which it was necessary 

 to follow was one of great simplicity. 



But if this mode of experiment, which we are about to describe, is 

 simple in itself, it is not the less surrounded by a multitude of difficul- 

 ties of detail, which cannot be removed without numerous attempts; and 

 I hope this will serve to excuse the incompleteness of these researches, 

 whicli I only give as the first rudiments of a more extensive investi- 

 gation. 



