ANATOMY. 
ik of external objects to be represented to the mind throngh the 
ne of the optic nerves. | ; 
HEARING. 
H is a sensation by which we perceive the sound of any 
agony. 
Sound is a tremulous motion of the air, excited by striking any 
sonorious body. “Sound is conveyed to an immense distance in the 
atmosphere, in | straight lines, which are called sonorous rays. Soft 
bodies diminish or stifle sound ; elastic ones increase it. eee 
_ of hearing is the soft portion of the seventh 
pulp is beautifully distributed in the porch, cular canals, and 
shell of the ear. Hearing is performed in the owing manner : the 
rays of sound emanating from a sonorous body, arrive at the ear, 
which, by its elasticity and peculiar formation, concentrates them, 
that they may pass along the external auditory or ear hole, to the = 
membranes of the drum, which they cause to vibrate The trem- 
bling drum conveys its vibrations to the hammer, which is in con= 
tact with it: the hammer communicates them to the anvil, the 
to the circular bone, and the circular bone to the stirrup. : 
rup adhering to the oval window, causes it to vibfate® ahis e 
communicates its vibrations to the water contained in the porch 
and semi-circular canals, and causes very gentle motions of the 
nervous expansion contained: therein, which transmi em to the 
sensorium commune, or seat of the mind, which hh 
presence of sound, and judges of its difference. Dee 
sharpness of sound depend upon the number of vibrations given at 
the same time. ae 
TASTING. sri, 
Tasting is a sensation by which we distinguish the qualities of 
ter, sw eet, sour, &c. substances. The nervous papille, or “fine 
points, of the tongue pairof nerves, which are distributed in the t 
and margins of the tongue, are the chief organs of taste. | 
parts subservient to taste, are: the tongue, which gives a conve 
Situation to the nervous papille, and by its extension. 
them to the substance to be tasted: the skin of the ton 
moderates any excessive stimulus: the saliva and mucus of the- 
mouth, which assist the organ of taste when it is necessary, that the _ 
substances ‘should be dissolved: inorder to be tasted, and which also _ 
= the nervous go moist. ‘ ae 
ae Sakic is a sensation by which we sh the | 
Se of hardness, softness, heat, and cold, &c. of bese sates 
Sipe: ere substance that comes in contact with the 
y at the points of the fingers. ‘Io great Sensation 
the skin, which also defends the 
