139 
ArtTIcuE VII. 
Researches on the Elasticity of Bodies which crystallize regu- 
larly ; by Fevrx Savarr. 
(Read to the Academy of Sciences of Paris, January 26th, 1829.) 
From the Annales de Chimie et de Physique, vol. xu. p. 5, et seq. 
Hiruerto 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 lamine parallel to certain faces of the crystal; but it has given 
us no information respecting the force with which these laminz 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 phenomena 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 
laminz 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 dises 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, 
which I only give as the first rudiments of a more extensive inyesti- 
gation. 
