472 SCIENTIFIC RECORD FOR 1882. 



other, or a single flame to strike upon a current of air. To avoid tedi- 

 ous adjustment, however, he prefers the following: A brass tube 25 cen- 

 timeters long and 33 millimeters in diameter is supported vertically. 

 By an opening at bottom a flame from a jet, having an opening which 

 is 2 millimeters in diameter, is projected horizontally across the tube. 

 By impact against the opposite wall of the tube, aided by the air cur- 

 rent, very pure sounds are produced. {J. Fhys., October, II, i, p. 461.) 



Decharme has studied the vibratory forms of circular liquid surfaces, 

 and finds very close analogies between these and those of soap films. 

 They are excited and observed similarly, and have the same system of 

 nodal points. The determination of intetnodal distances is more diffi- 

 cult with liquids, since they are only one-sixth as great. But the laws 

 are the same; the distances of the iuternodes are inversely proportional 

 to the number of vib: ations. {Ann. Chim. Phys., January, Y, YXV, p. 112.) 



Kolacek has investigated mathematically the theory of resonance, and 

 has demonstrated that tbe conductibility of gases for heat has only an 

 exceedingly minute influence on the number of vibrations made by the 

 gas confined in a resonator. With a Ilelmholtz resonator, making 198 

 vibrations a second, the sound is lowered only 0.152 vibration, an unim- 

 portant amount. ( Wied. Ann., xii, j). 353 ; J. Phys., January, It, i, p. 58.) 



Hurion has proposed to determine the position of the nodes and 

 loops in an organ pipe by means of a tube introduced into the pipe, 

 this being in communication with a manometric capsule. [J. Phys., 

 March, II, i, p. 136.) 



Serra-Carpi has made use of the microphone for fixing the position of 

 the nodes and loops in vibrating columns of air. (Jpon a membrane 

 stretched on a metal ring a small carbon microphone is placed. When 

 at a node a loud rattle is beard in the connected telephone; when at a 

 loop the sound is feeble. {Comptes Rendus, January, xciv, p. 171.) 



Leconte Stevens has combined the organ pipe with the sonometer, 

 forming an instrument which he finds very convenient for the exhibi- 

 tion of Bernouilli's laws, and for the study of upper partial tones and 

 musical scales. {Am. J. 8ci., June, III, xxiii, 479.) 



Bourbouze has proposed the use of a sounding board furnished with 

 strings, upon the back of which is a carbon microi^hone, as a telephone 

 trausttiitter. {Comptes Rendus, January, xciv, 76.) 



Hartmann has devised several new pieces of acoustic apparatus. The 

 motorophone consists of a shaft carrying an eccentric communicating by 

 means of a rod with a membrane. It converts rotary motion into sound, 

 the pitch being determined by the speed, and the intensity by the throw 

 of the eccentric. A bell mouth strengthens the tones. The pJionomotor 

 acts on the opposite principle, producing rotary motion from vibration. 

 In the electromagneiophone a piece of sheet-iron under an electro-magnet 

 has a point dipping in mercury ; a current passing through the coils 

 and the point is rendered intermittent, and the membrane sounds. The 

 electro-magnetic membrane syren is similar, but lias a solid sliding contact 



