110 M. Savart's Researches on the structure of Metals, S^c. 



of elasticity, of which one of the axes was in the plane of the 

 plates. 



From these researches it follows, that the differences of re- 

 sistance to flexion in different directions of the same mass of 

 metal may be much greater than in certain woods, such as oak, 

 beech, &c. since we meet with circular plates of metal whose 

 two Kounds differ a fifth, and that in the woods which we have 

 mentioned the interval between the two sounds does not exceed 

 a third minor for directions where the differences of elasticity 

 are the greatest ; and yet, as we have formerly established, 

 the extreme elasticities are as 1 to 16. 



The influence of annealing appears to be very feeble or per- 

 haps nothing when the metals have not been hammered ; for se- 

 veral discs of copper which had been exposed during several 

 hours to near their melting heat still emitted the same sounds 

 which they had produced before this operation. But it is not 

 so when the plates have been previously hammered, and then 

 re-heated, for it often happens that the interval between the 

 two sounds varies a little, and that there is some change in the 

 disposition of the nodal lines. 



The phenomena which we have observed in metals are far 

 from being peculiar to them. Analogous ones occur in glass, 

 sulphur, common resin, copal, amber, plaster, slates, &c. The 

 interval between the two sounds of different plates of these 

 substances is always very small. It rarely exceeds a semitone 

 major, and the two modes of division, though they constantly 

 affect a fixed position, differ so little from one another that they 

 always appear in the form of nodal rectangular lines. Among 

 the bodies which I have examined, Spanish wax is the only 

 case in which the system of two nodal rectangular lines may 

 be found indifferently in all directions ; but this substance 

 being a simple mixture of lac, turpentine, and cinnabar, we 

 may conceive that the last ingredient, which is in a pulveru- 

 lent state, prevents the particles of the resin from taking a re- 

 gular arrangement 



I shall conclude this memoir with an observation applicable 

 to all bodies which do not crystallize regularly : Immediately 

 after they become solid they in general sound with much less 

 facility than they do in some hours, some days, or even some 



