182 ANNUAL OF SCIENTIFIC DISCOVEUT. 



Thf ililTerent disks are intended to represent different acoustical 

 plicnonnMia, as interference, beats, the harmonics, etc. 



Among the instruments is a complete apiKvratus for resonance. 

 This consists in a series of nineteen hollow copper globes, 

 arraiip^fil :u'L-oi-tlin;^ to ci-rtain notes. Each of the jrlobcs is fur- 

 nished with two o])enings, one of which estal»lishcs a comiiiiiiiica- 

 tiou with the air, whilst the other is connected with a little tube 

 to be i)lac('d in the car. If any of the harmonics accompanying 

 the fundamental sound contain the proper note, a powerful res- 

 onance is iicard. 



Esjx'cially worthy of notice is a large apparatus for the artificial 

 composition of diilerent kinds of sounil, by the simultaneous pro- 

 duction of a series of simple notes. Kiii;ht tuning-forks arc lixed 

 vertically between the arms of eight horizontal electro-magnets, 

 round which jiasses an intermittent current. The interruption in 

 the current is ))roduced bj' a fork making a certain number of vi- 

 brations between the poles of an elect ro-magnet. In front of each 

 tuning-fork is a resonant tube, the o])cniMg into which can be more 

 or less closed by means of a movable st(jp. When the opening 

 is entirely closed, the tuning-forks can be scarcely heard ; but 

 any desired note can be obtained by withdrawing the key which 

 closes the resonant box. 



Singing Flames. — There is a pretty modification of one of 

 Count Schatfgotsch's experiments on singing flames. Two little 

 jets of gas issue from two tapering inu'ners. Over the flames are 

 placed two glass tubes nearly in unison. When the flames begin 

 to sing, beats are heard corresponding to the viijratory movement 

 of the flames ; a phenomenon first explained by Professor Tyn- 

 dall, in the '• Philosophical Magazine," for July, 1^57. So fai', 

 the experiment is old ; but now M. Koenig causes one of the 

 burners to be rapidly rotated along with a revolving mirror. The 

 broken luminous circle given l)V the singing flame when unmoved 

 ia, when it rotates, changed into a discontinuous crown of light, 

 which appears to be formed of luminous pearls as soon as the 

 flame in the other tube is made to vibrate. By another arrange- 

 ment, the flames can be made to take the aiDpearance of a double 

 spiral. 



Fhonautograph. — Hitherto we have mainly trusted to the ear 

 to inform us of the existence of vibrations. M. Koenig now 

 details apparatus by which observations can be made without the 

 use of that organ. 



For this purpose, by far the most important instrument is the 

 phonautograjDh, which writes in the form of a curve not only in- 

 strumental notes, but also some of the simpler vocal sounds. 

 Experiments on the phonautograph have recently been made by 

 !Mr. Bonders, who has sent a preliminary note on the sul)ject to 

 " PoggendorfTs Annalen," from which we have obtained the fol- 

 lowing particulars: The instrument, as used by Mr. Bonders, 

 consists in a delicate stretched membrane, to which is attached a 

 light weight, and of a pen for writing the motions of this mem- 

 brane. Tlie pen employed consists of s(3veral elastic tongues 

 springing from a bent holder, and so fixed that the teeth of the 



