28 Patent Ear-trumpet. 
which they pass into the head. Ina short distance this 
tube has its passage stopped by a thin membrane—the 
drum of the ear—stretched tightly across it. Behind this 
lies a cavity, the “barrel of the ear” or tympanum, through 
which runs a chain of four small bones connecting the drum 
of the ear with the sensorium. These bones are supposed to 
continue the vibration produced upon the drum by the 
vibratory action of the air, towards the sensorium, whence 
the brain receives its impressions. 
Thus, from the disorder of any one of these organs, we 
may readily conceive how various may be the causes from 
which deafness may arise. If the inner ear or sensorium 
remains perfect, the loss of hearing produced by the destruc- 
tion of the drum, or the derangement of any of the other 
parts of the ear, can be in many cases remedied by the use 
of instruments which will convey a greater degree of sound 
than that which the ear alone receives, 
On the other hand, I have been given to understand that, 
if deafness arises from the disorder of the sensorium, no 
introduction of increase of sound will assist the hearing ; for 
according as the auditory nerve is capable of receiving the 
vibrations imparted to it, in the same measure will be its 
power of communicating to the brain the impressions those 
vibrations produce. It would therefore appear evident that 
the advantage deaf persons will derive from the use of 
ear-trumpets will depend in a great measure, if not entirely, 
on the nature of their deafness. 
There are two kinds of ear-trumpets commonly used ; one — 
consisting of a long indiarubber tube fitted with an ear- 
piece at one end, and at the other a bell-shaped piece into 
which it is necessary to speak when addressing the deaf 
person. This, therefore, cannot be made use of on all occa- 
sions; the mode of using it also renders it very inconvenient. 
The other trumpet is simply a small funnel-shaped instru- 
ment, curved at the‘narrower end, which is inserted in the 
ear. The only apparent object of this instrument is to 
reflect that amount of sound received at the large end to the 
smaller, where it is collected as it were into one point, and 
in this condensed state is rendered more audible than could 
have been effected by the ear alone. It is to an improve- 
ment on this latter trumpet that I would now direct your 
attention. It consists simply of two tubes; one inside, the 
other but only connected at the smaller end. The object of 
this double arrangement is to prevent the hand or any other 
