1917] on The Organs of Hearing in Relation to War 1)5 



many of the cases of war-deafness. Inflammatoiy conditions of the 

 ear freqnentlj arise as the result of exposure to cold or damp or 

 infectious disease of various kinds, including mumps and epidemic 

 cerebro-spinal meningitis, popularly known as spotted fever. The 

 latter is the cause of some of the most deplorable cases. 



The hearing-power in general is tested bv means of the voice, the 

 watch, and numerous other sources of sound, but the extent of hearing 

 for tones of various pitch is usually measured by means of tuning- 

 forks. [The lecturer pointed to a fallacy in the use of tuning-forks, 

 viz. that the hearing-power is usually calculated as in direct propor- 

 tion to the length of time the tuning-fork is heard. In reality the 

 tuning-fork dies away in proportion to the logarithm of the time, i.e. 

 the Xaperian logarithm. The lecturer had dealt with this question 

 in a paper read before the International Otolo2:ical Congress held at 

 Boston, U.S.A., in 1913.] 



For the highest pitched tones the hearing was tested by means 

 of Galton's Whistle, the steel wire or monochord, or small steel 

 rods. Retention of hearing for these tones indicates integrity of the 

 most vulnerable portion of the cochlea (i.e. the portion nearest the 

 base, with the shortest fibres), and hence greater probability of 

 recovery. 



The equilibrial jJortmi of the tahyrinth consists mainly of the 

 semicircular canals forming the posterior half of that organ. [Their 

 structure was shown by large diagrams and their small size by the 

 actual human skull] They lie in three planes, so that they are 

 displaced by movement of the head in any direction whatever. Inside 

 their membranous lining there is a fluid which lags or continues in 

 movement when the canal is moved or when it stops, thus disturbing 

 the hairs on certain minute cells in the dilated portions of the tubes. 

 These hair-bearing cells are connected by nerves with certain nuclei 

 and with the cerebellum and spinal cord. They have also important 

 communications with the nuclei of the nerves which control the 

 movements of the eyeballs. The eyeballs enter into appropriate 

 movements when the position of the head changes, and this is induced 

 by the disturbance set up in the semicircular canals. If we rotate 

 a person with normal semicircular canals the eyes make definite 

 jerking movements, and if these movements do not take place we 

 assume that the semicircular canals are damaged. If again we apply 

 cold to the labyrinth, downward currents are produced and jerkings 

 of the eyeballs follow. [The lecturer illustrated the effects of rotation 

 by means of a circular trough filled with water in which stood some 

 flexible reeds. He also explained the formation of downward con- 

 vection currents in a large beaker of water, on the surface of which a 

 lump of ice was placed. Upward currents were shown by means of a 

 spirit-lamp below a beaker of water.] 



The " walking-stick " test introduced by Prof. Moure, of Bordeaux, 

 is carried out as follows : The subject bends down, rests his forehead 



