170 



THE POPULAR SCIENCE MONTHLY 



The rhinoscope also enables us to examine the nasal or pharyn- 

 geal orifices of the Eustachian tubes. These latter are passages lead- 

 ing from the inner side of the drum of the ear, and opening, as 

 already indicated, at a point situated in the posterior nasal parts. 

 It is not the province of this article to enter into minute or pre- 

 cise detail, and therefore we shall merely add that these tubes 

 bear a very important relation to the faculty of hearing. If the 

 nasal orifices of these tubes become swollen by disease, or choked 

 with diseased mucus, greater or less impairment of the hearing-power 

 results. Consequently, the rhinoscope has rendered no small service 

 to us for determining causes of deafness, and of curing them, which 

 formerly were but guessed at or remained unknown. 



But to make the laryngeal and rhinal mirrors available, the artifi- 

 cial illumination of these parts is necessary. To depend upon the sun's 

 rays, as was the case with the original experiments, was too uncer- 

 tain. Czermak,as we have seen, substituted artificial light, and thus 

 enabled an examination to be made at any hour of the day or night. 

 Tobold, of Berlin, after a time, brought forward an apparatus which 

 is depicted in the following cut, and which embodied the most perfect 

 apparatus of the time. The cut also shows us the position of the 

 patient and of the examiner. 



As introduced by him, it consisted of a common stucly-lamp : a 



Fig. 2. 



is a brass tube, or light-condenser, in which are convex lenses, c, d, g. 

 The lenses c and d, it will be observed, are close together, while the 

 third, ff, is at the distal extremity of this brass tube. At/ this brass 

 tube can be unscrewed, thus enabling the cleansing of the lenses. 



