312 SCIENTIFIC NEWS. 



contribute equally to the advancement of natural philoso- 

 phy and mathematics. 

 Chladni. Happily Mr. Chladni has done for the vibrations of elas- 



tictic surfaces what Sauveur did a century ago for the 

 stretched chord. He has discovered, and rendered pereep- 

 tibleln a very ingenious manner, by the arrangemct dry 

 sand takes on vibrating plates, undulations with points of 

 rest interposed. His majesty the emperor and king, who 

 has seen the experiments of Mr. Chladni, struck with the 

 influence that the discovery of a strictly accurate theory, 

 capable of explaining all the phenomena rendered sensible 

 by these experiments, would have on the progress of natu- 

 ral philosophy and mathematical science, has desired the 

 class to make it the subject of a prize, to be projx>sed to all 

 the learned of Europe. The class accordingly .announces 

 it in these terms. 



Prize question. '« To give the mathematical theory of the vibrations of 

 " elastic surfaces, and compare it with experiments." 



The prize will be a gold medal of the value of 3000 f. 

 [ £125], to be awarded at. the public meeting on the tilth 

 mmday in January, 1812. No work will be received after 

 the 30th of September, 1811. 



Report nn Mr. The following is an abstract of the report adopted by the 



Clilarhu's . . ..■■•■ . 



Theory of class of mathematical and physical sciences, and that of the 

 Sound. fine arts, on the 13th of february and 18th of march, 1809, 



on Mr. Chladni's work concerning the theory of sound. 



Thi6 treatise, published in German in 1802, and about to 

 be translated into French, contains every thing of impor- 

 tance in his first work, which appeared in 1787» and is en- 

 larged by considerable additions. Under the title of acous- 

 tics, it is divided into four parts, which treat, 1, of the nu- 

 merical ratios of the vibrations of sonorous bodies ; 2, of the 

 laws of the phenomena they exhibit; 3, of the laws of the 

 propagation of sound ; 4, of the physiological part of a- 

 coustics. » 



"Number of vi- The first contains little but what is already known.' To 

 determine the absolute number of vibrations in a note how- 

 ever, Mr. Chladni does not employ a chord, but a slip of 

 metal fixed at one extremity, and long enough to allow the 

 oscillations it makes in. a given time to be counted. Their 



number 



brariop.s in 

 notes. 



