58'2 SCIENTIFIC RECORD FOR 1883. 



density, though less rapidly, and varies inversely as the compressi- 

 bility. (Wied. Ann., xvn, 964; J. Phys., September, 1883, II, n, 422.) 



Wead, in a valuable memoir on the energy and coefficient of damp- 

 ing of a tuning-fork, intended as the first part of a research on the 

 intensity of sound viewed from the standpoint of energy, has discussed 

 the theory of the subject and compared the results with those obtained 

 from direct experiment. The forks used were Koenig's, and the energy 

 in both prongs, when z is the amplitude, expressed in divisions of a 

 micrometer, 220 of which were equal to 1 centimeter, was found to be as 

 follows : For the Ut 2 fork, z x450 ergs ; Ut 3 , zx 1,235 ergs; Mi 3 , 1,820; 

 Sol 3 , 2,250; Ut 4 , 3,860; Sol 4 , 7,500; Ut 8 , 12,670 ergs. From the time 

 required by the fork to decrease the amplitude of its vibration by 

 a known quantity, the coefficient of damping was calculated. The 

 forks were then taken on : of doors and the amplitude observed at the 

 instant a distant listener indicated that the sound ceased, the object 

 being to determine how much energy was needed to cause sensation; 

 i. e., how much energy passed through one square centimeter at the limit 

 of hearing. For the Ut 3 fork this was found to be, at 200 feet, 280 x 10~ 8 , 

 and at 300 feet, 310 x 10" 8 ; for the Sol 3 fork at 200 feet, 260 x 10- 8 ; for the 

 Ut 4 fork, 110 x 10- 8 ; and for the Ut 5 fork, 710 x 10~ 8 . The energy of a 

 fork is dissipated (1) in heating itself and the resonance box (2) in 

 causing its support to vibrate and (3) in producing a sound wave. 

 Some experiments to determine the relative energy so distributed 

 showed that only about one-fifteenth of the total energy is used for the 

 sound wave. (Am. J. Sci., September, 1883, III, xxvi, 177.) 



Dvorak has continued his investigations upon the attractions and 

 repulsions produced in the vicinity of vibrating bodies. He shows 

 from theory that the mean pressure in the vicinity of the nodes is supe- 

 rior to that at the loops, a result which he has confirmed by experi- 

 ment. By this excess of pressure on the base of the resonnators the 

 author explains the repulsion of these by sonorous bodies. He has de- 

 scribed some new rotation apparatus, more perfect than that used 

 hitherto. For obtaining the best result it is necessary that the vibra- 

 tions should be energetic, and to secure this the walls of the resonance 

 box should vibrate in unison with the fork mounted upon it. A form 

 of torsion balance, with bifilar suspension, by which, on this principle, 

 the intensity of the air vibrations may be measured, is described in the 

 paper. (.7. Phys., October, 1883, II, 11, 465.) 



Neyreneuf, by means of a special apparatus, has studied the capa- 

 bility of various gases for transmitting sound. A tube of iron, 2 meters 

 long and 5 centimeters diameter, the ends closed by suitable mem- 

 branes, is passed through the wall separating two rooms. In one of 

 these is the sonorous body and in the other the sensitive flame. The 

 gas is introduced by lateral tubulures. The sensitive flame remains 

 fixed in position and the tube is moved until the effect on the flame is 

 zero. The results show that air and carbon monoxide have appreciably 



