RELATIONS TO OTHER SCIENCES 457 



the employment of the principle of stereoscopy in order to substitute 

 photographs, the plasticity of which truly rivals life, may fairly be 

 described as a triumph in utilizing for our special purposes the 

 achievement of an apparently very remote science. 



The mention of electricity, the X-rays, and radium naturally brings 

 to our minds the fact that the chapter on light is of interest to laryn- 

 gologists and rhinologists, not from the point of view of the question 

 of illumination alone. We are privileged to live in a time when the 

 great healing powers of light have been discovered and are utilized 

 in a class of cases in which there is much need for addition to our 

 therapeutic armory. The light of the sun, the electric light, the 

 ultra-violet rays, and the emanations of radium are nowadays util- 

 ized with much success for the treatment of lupus, of rodent ulcer, 

 and of some of the more superficial forms of malignant disease; and 

 it may fairly be hoped that further progress may be made in the 

 treatment of these cruel affections even when they occur in parts 

 not easily accessible to the effects of the various rays. 



(6) Sound. Whilst the chapter of physics dealing with light and 

 its powers is, as I have just endeavored to show, of the very highest 

 importance for laryngology and rhinology, the chapter on sound 

 holds an equally high position with regard to otology. I need not 

 elaborate that a science which is prominently concerned in dealing 

 with the troubles of hearing is inseparably connected with the physics 

 of sound. Thus the tuning-fork is one of the most indispensable 

 weapons of the aurist, and the question whether the sounds caused 

 by its vibrations are more easily perceived by aerial or by bone con- 

 duction is of the highest diagnostic importance in a large number of 

 ear affections. In the same category may be mentioned Galton's 

 whistle for the testing of the hearing of high notes. Again, the ques- 

 tion of the capacity for the perception of tune; the difference in 

 perception according to whether the mouth is closed or open; inter- 

 ference phenomena; the estimation of the hearing capacity for 

 speech; the audibility of different sounds; the differential diagnosis 

 between affections of the sound-conducting and sound-perceiving 

 apparatus are all questions intimately connected with the physics 

 of sound, and it might be said without exaggeration that otology 

 without constant close relationship with physics is an impossibility. 



The Phonograph. Speaking of sound, the phonograph, an in- 

 vention due to American genius, must not be forgotten, although 

 its possibilities in connection with our triad are still in their infancy. 

 I may remind my hearers that very shortly after its introduction 

 Dr. Mount Bleyer of New York, Dr. Lichtwitz of Bordeaux, and 

 I, independently of one another, conceived the idea of utilizing 

 its recording powers for the purposes of instruction. One does not 

 always have a case of whooping-cough at hand if one lectures on 



