344 PHYSICS. 



sound was lowered in pitch, (2) it was more decided the more dense the 

 liquid, (3) it was much more marked when the bell was wholly immersed 

 in the liquid than when the liquid was simply contained in the bell, and 

 (4) in both cases acute sounds were less lowered than grave ones. 

 The lowering of the sound was more decided with water than with al- 

 coliol and ether. {Nature, January 20, 1881, xxiii, 278.) 



Ellis has presented a paper to the Eoyal Society on the influence of 

 temperature on the musical pitch of harmonium reeds, giving the results 

 of experiments on the harmonium reeds of Appunn's treble tonometer 

 at South Kensington Museum, at temperatures differing by from 20° to 

 20O F. These experiments make it probable that the pitch of such reeds 

 is affected by temperature to twice the extent of tuning-forks and in the 

 same direction ; that is, they are flattened by heat and sharpened by 

 cold about one vibration in 10,000 per second for each degree Fahrenheit. 

 {Nature, February, 1881, xxiii, 379.) 



Eoig and Torres have substituted for the metallic diaphragm of the 

 phonograph a mica plate quite free at the border and supported at the 

 center by an axis of caoutchouc fixed to a small spring. Besides the 

 short style for indenting the tinfoil, this axis carries a piece of metal 

 which supports a second style perpendicular to the first, the vibrations 

 of which are inscribed on a smoked cylinder. By clockwork the same 

 angular velocity is imparted to both cylinders, so that while the short 

 style makes its usual marks on the tin foil the long one produces a larger 

 tracing on the smoked surface. In these traces the authors have suc- 

 ceeded in recognizing the vowels, some consonants, and even some syl- 

 lables, but they have not been able to read entire phrases. {Nature, 

 February, 1881, xxiii, 373.) 



Koenig has studied the beats and beat-tones of harmonic ii^tervals, 

 and concludes against the view of Helmholtz, that these are due to har- 

 monic tones of the lower primary sounding with the higher. He has 

 produced the phenomena by means of a " wave siren," consisting of a 

 rotating disk or cylinder, the border of which is cut so as to represent 

 with great accuracy the curve produced by the combination of two sim- 

 ple tones. "When a blast of air is directed against this serrated edge 

 through a slit, an air motion is produced quite like that produced by 

 the two tones sounded together, and in which the beats and beat-tones 

 are heard. When the border is a simple harmonic curve and the slit at 

 right angles to it, a simple tone only is heard ; but if this slit is slanted 

 a. little a ''clang" is at once develoj)ed with strong overtones. On 

 Helmholtz's supposition, the beat-tone obtained with two simple tones, 

 the slits being at right angles, should be less distinct than when the 

 overtones are brought out by slanting the slits ; whereas in point of 

 l^ct the precise reverse of this is the case. ( Wied. Ann., 1881, II, xii, 

 335; Nature, April, 1881, xxiii, CIG, August, 1881, xxiv, 358.) 



Koenig has described a simple and very efficient lecture apparatus 



