336 Dr. Weber on Savart' s Experiments on the 



thor, the greatest side of which is nearly fifteen (German) geo- 

 graphical miles, and in which the excess of the sum of the 

 three angles above two right ones is nearly fifteen seconds, the 

 three reductions of the angles to angles of a rectilinear trian- 

 gle are 4"'951 13, 4"*95104., 4"*95131. The author has, how- 

 ever, likewise calculated the terms of the fourth order wanting 

 in the above expressions, which assume for the sphere a very 

 simple form ; but in measurable triangles on the surface of the 

 earth they are quite insensible; and, in the above example, they 

 would have diminished the first reduction by only two unities 

 in the fifth decimal place, and have increased the third reduc- 

 tion by the same amount. 



LIU. On Savart's Experiments on the Motions of mediately 

 agitated Membranes. By Dr. Wm. Weber, Academical 

 Teacher at Halle*. 



[With an Engraving.] 



" Tj^ROM the manner just stated of the division of mem- 

 -*- branes into vibrating divisions," says Savart, in the Ann. 

 deChim. ctdePhys. (1826. torn, xxxii. p. 385.) " it is evident 

 that the acoustic figures called by Chladni distortions, form 

 the transition between a variety of figures of sound which are 

 not distorted (in which may be reckoned several tones of the 

 flageolet). As Chladni has only observed the distortions of 

 figures of sound which are nearest the undistorted figures 

 (which he considers as fundamental figures), and as he fixed 

 the number of vibrations merely by the ear, which does not 

 admit of sufficient accuracy, he might justly assert that the 

 tone in the distortion of the figures of sound is the same as in 

 the fundamental figures. But in the tables accompanying his 

 Traite aV Acoustique, we find distortions of figures of sound 

 to which belong semitones, a whole tone, and even one-third 

 higher than when the figure of sound has what is termed the 

 fundamental form." The difference between Chladni and 

 Savart, according to these observations of the latter, is, that 

 Chladni asserts that there is in sounding plates no transition 

 from one tone of the flageolet to another ; whilst SaVart says 

 that by a repetition of experiments, he has discovered this 

 transition. 



Savart justly says, that nothing in nature appears isolated. 

 He has actually shown in this treatise, as well as in some 

 former ones, an extraordinary number of transitions of one 

 kind of vibration into the other, in almost all bodies used for 

 musical purposes. Elut it is also a universal rule of nature, 



* From Schweigger's Jahrbuch dor Chemie, &c, N.R. Band xx. p. 176. 



that 



