456 OTOLOGY AND LARYNGOLOGY 



tion of light for the use of laryngology, is stroboscopy. By an in- 

 genious modification of the stroboscope, consisting of two rotatory 

 disks, the one perforated, whilst on the other figures are drawn, which 

 are inspected through the perforation of the first disk, the late Pro- 

 fessor Oertel has succeeded in constructing an apparatus by means of 

 which the oscillation of the vocal cords can be accurately observed. 

 Very interesting observations on the action of the vocal cords during 

 singing have been made with the aid of this apparatus, as an exam- 

 ple of which I may only mention that, according to Oertel, "the 

 sounds of the chest register are produced by oscillation of the vocal 

 cords in their entire length and breadth, whilst the sounds of the 

 falsetto register are caused by the longitudinal division of the sur- 

 faces of the vocal cords into aliquot parts, nodules being at the 

 same time formed on them." 



Photography. A further method to be mentioned in this connec- 

 tion is photography. I need not say that photographic reproduction 

 of preparations illustrating the normal and pathological anatomy 

 of the ear, the nose, and the throat is no exclusive property of laryn- 

 gology, rhinology, or otology, but a special interest connects the 

 former of these sciences with photography, inasmuch as by the aid 

 of this method a number of most interesting observations have been 

 made on the physiology of the larynx during the act of singing. The 

 method has proved particularly useful in showing the absurdity of 

 the preconceived ideas of some teachers of singing as to the extent 

 of the individual registers. It has fully corroborated the views held 

 by those most competent to speak as to the enormous variety in pro- 

 ducing the singing voice, even in persons whose voices belong to one 

 and the same category. The pioneer in this fascinating territory has 

 been an American, my friend Dr. French of Brooklyn, and to his 

 enthusiasm and perseverance have been due the first reliable results 

 of this most promising method of physiological investigation. Fur- 

 ther studies in this direction have been made by Dr. Musehold and 

 Professor E. Meyer of Berlin. The last-named gentleman has just, 

 in cooperation with the celebrated mechanician, Zeiss of Jena, con- 

 structed a very ingenious apparatus for demonstrating and photo- 

 graphing the larynx; but having seen the photographs obtained by 

 its use, I am bound to say that the work done by Dr. French has not 

 been so far surpassed. 



Stereoscopy. Finally, in connection with light, I must not omit to 

 mention the ingenious application of stereoscopy for purposes of 

 medical teaching made by my friend Dr. Watson Williams of 

 Clifton in the wonderful atlas which accompanies the second edi- 

 tion of his work on Diseases of the Upper Respiratory Tract. It 

 being often extremely difficult to obtain, for teaching purposes, 

 really illustrative preparations of the accessory cavities of the nose, 



