PHYSICS. 251 



Sedley Taylor lias given the name plioneidoscope to an apparatus for 

 studying the character of sound vibrations by causing them to act on 

 a liquid film tliin enough to give color, such us a film of glyceric liquid, 

 Guebhard has proposed a modification of the method by which he has 

 obtained some very curious results. Beautiful interference rings are 

 produced by the condensation of the vapor of water upon the freshly 

 cleaned surface of a very impure mercury. When, for example, the 

 various vowel sounds are emitted above such a mercury surface, with a 

 pure tone maintained for some seconds, at a distance so small that the 

 vapor of water contained in the breath has not time to diffuse, a series 

 of figures are obtained which are characteristic. Figures are given of 

 the ten principal vowel sounds thus produced. The four nasal vowels 

 give more complex figures. — [J. rin/s., ix, 242, July, ISSO.) 



Barlow has constructed an apparatus for recording the sounds of the 

 human voice, which he calls a logograph. It consists of a small trumpet- 

 shaped mouthpiece, the larger extremity of which widens to a diameter 

 of 7 centimeters. Over this end is fiistened a thin caoutchouc mem- 

 brane. A light arm of aluminum is fiistened at one end to the frame, 

 and the other, w^hich presses against the center of the membrane, with 

 which it is movable, carries a small brush containing color. A band of 

 paper, like that used in the telegraph, passes beneath, so that the point 

 of the brush just touches it, and traces a line upon it when the mem- 

 brane is at rest, which is a zero line. There is a small lateral opening 

 in the mouthpiece for the escape of the air. Various examples are given 

 of the results obtained in using the logograph for spoken language. — {J. 

 Phys., viii, 78, March, 1870.) 



Dvorak has observed that light resonators of glass or metal are re- 

 pelled very decidedly wheu they are brought near to the resonance box 

 of a fork turned in unison with them. The condition essential to the 

 success of the experiment is that the air of the resonance box shall be 

 really in vibration. A metallic disk in unison with the resonator may 

 also be used as the vibrating body. The repulsion thus produced is so 

 strong that when a mill is constructed with four resonators at its ends 

 and placed before the resonance box of a large fork, the mill revolves. 

 Mayer independently discovered the same phenomenon. — {Phil Mag., 

 V, vi, 225, 1879.) 



HEAT. 



1. Thermometry and Change of State. 



Benoit has described a new temperature-regulator based upon the 

 principle of the variation of the tension of a saturated vapor with the 

 temperature, first employed by Audreie. The apparatus consists of a 

 small bulb, containing the volatile liquid, placed in the space whose 

 temperature is to be maintained constant. The end of the tube on 

 which this bulb is blown is connected with a gas-interrupter by means 

 of a rubber tube filled with mercury. This interrupter consists of a 



