PHYSICS. 471 



(luced by the flow of liquids from orifices according as the walls are thick 

 or thill, to the construction of a tuning fork which he calls a hydrodia- 

 pason. It is formed of a tube of brass 0.5 meter long, C millimeters 

 in interior diameter, and 1 millimeter thick, curved into an elongated 

 U, the branches being 6 centimeters apart. On the convexity of the 

 curve is an opening through which connection is made with the water 

 supply. Tlie extremitj^ of each branch is bent so that the ends open 

 exactly opposite each other. To these, disks or ajutages of any form 

 may be attached. When the current of water flows, the fork takes a 

 rejiular rate of vibration and gives a clear note. In water the tone 

 given was Ici (217.5 vibrations), and the first harmonic was plainly heard. 

 [Comptes Eendus, October, xcv, p. 597.) 



Pinto has studied the function of two ears in determining the direc- 

 tion of sounds, and concludes, 1st, that we are able to judge of the di- 

 rection from which a sound comes because it reaches one of the ears 

 first and then the other, the interval of time being longer or shorter 

 according to the position of the sounding bod^^; and 2d, that the second 

 ear enables us to determine the direction in which the intensity of the 

 sound j)erceived is a maximum without turning the head. {J. PJiys., 

 December, II, i, j). 561.) 



Stanley has presented to the London Physical Society a paper on 

 tuning-fork vibrations. He showed that disks on the prongs of a heavy 

 fork do not produce as loud a sound when the fork vibrates as does its 

 resonator; that vibration down the stem of the fork does not, as Chlad- 

 ui supposed, depend on a vibrating ventroid, since a fork cut in the 

 end of a solid steel bar communicated sonorous vibrations equally well 

 to the resonator. Since to set a iork vibrating only one prong need be 

 bowed, it is evident that the vibration must proceed along the prongs. 

 A light fork, a meter long, shows the passage of the vibrations down 

 one prong and up the other. When the i)rongs of a powerful fork 

 are tipped with pieces of metal dipping in mercury, the mercury is 

 thrown into rii)ples which can be thrown on a screen, {Nature, June, 

 XXVI, p. 100.) 



Koenig has published in book form the valuable researches in exper- 

 imental acoustics which he has made during several years past. The 

 most recent and one of the most important of his investigations is that 

 undertaken to determine the influence of phase on the quality of tone. 

 He finds that, contrary' to the theory of Helmholtz, there is a distinct 

 difference in tones containing identically the same upi)er partials when 

 the phase differs. The sound is louder and more forcible whcMi this dif- 

 ference is one-fourth, gentler and softer when three-fourths. By means 

 of a specially-constructed wave-syren he has elaborately studied these 

 phenomena. {Qiielques Experiences (VAcoustique, Paris, 1882; Nature, 

 June, July, xxvi, pp. 203, 275; J. Phys., December, II, i, p. 525.) 



Neyreneuf has contrived a sensitive flame without an inclosing tube. 

 This is attained by causing two flames to impinge the one upon the 



