RELATIONS TO OTHER SCIENCES 453 



ties have developed so much along characteristically independent 

 lines that theoretically one might be inclined to think that they had 

 comparatively little in common with other branches of medicine, let 

 alone other sciences and arts. 



Nothing could be better calculated to destroy such mischievous 

 belief than the results of my inquiry. At every step during the pre- 

 paration of this paper has it become clearer to me how much we owe 

 to apparently remote lines of human thought, how much we have 

 been and are benefited in our special work by progress made in other 

 distant fields, and how much more good we may expect to accrue to 

 us from the advances achieved in territories of human thought 

 which a few years ago even the most fantastic visionary could not 

 have brought into useful combination with our own occupation. 



It will be my endeavor in this address to justify the foregoing 

 statements by rapidly surveying the intimate connection of laryn- 

 gology, rhinology, and otology in addition to their relations with 

 other branches of medicine - - with physics, chemistry, mathe- 

 matics, philosophy, history, biology, technology, and music, and I 

 only regret that within the limit of time allotted to me it will be 

 quite impossible to do full justice to my task. 



I. Physics 



(a) Light. Let us first take physics. The connections of that 

 science with laryngology, rhinology, and otology are as manifold as 

 they are interesting and important. The branches of medical science 

 named have it in common that they deal with the investigation of the 

 physiology and pathology of deep-seated cavities. Hence the ques- 

 tion of their illumination for purposes of examination is of the great- 

 est importance, and thus the chapter of physics dealing with the 

 properties of light is a subject of immediate and pressing interest 

 to us all. This applies with particular force to laryngology. Although 

 of late, through the work of Kirstein, direct inspection of the larynx 

 by means of depressing the tongue with suitable spatulas has been 

 rendered feasible, this method of examination is only applicable in 

 a certain fraction of cases, and examination of the larynx is still 

 carried out universally by means of reflecting mirrors. The very 

 foundation of laryngoscopy, as ordinarily practiced, depends upon 

 the principle of physiological optics: that when rays of light fall 

 upon a reflecting surface placed in a certain inclination towards the 

 source of light, the angle of reflection is equal to the angle of inci- 

 dence. Thus, if a small mirror be held at an angle of 45 degrees to 

 the horizon just below the uvula, whilst a powerful beam of light is 

 thrown horizontally into the throat of the person examined, the part 

 just underneath the mirror, that is, the larynx, becomes illuminated 



