7g THE HORSE. 



likewise supported and moved by a third small cartilage, placed at the 

 fore part of the base of the conch, and into which several muscles are in- 

 serted. 



The ear is covered by skin thinner than in most other parts of the 

 body, and altogether destitute of fat, that it may not be too bulky and 

 heavy, and may be more easily moved. Under the skin lining the inside 

 of the cartilage are numerous glands, that secrete, or throw out a scaly 

 white greasy matter, which may be rubbed off with the finger, and which 

 is destined to supple this part of the ear, and to keep it soft and smooth. 

 Below this are other glands which pour out a peculiar, sticky, bitter fluid, 

 the wax, probably displeasing to insects, and therefore deterring them from 

 crawling down the ear, and annoying the animal : or by its stickiness arrest- 

 ing their progress. 



The internal part of the conch is covered with long hair which stands 

 across the passage in every direction. This likewise is to protect the 

 ear from insects, that would with difficulty penetrate through this thick 

 defence. The cold air is likewise prevented from reaching the interior of the 

 ear, and the sound is moderated, not arrested ; penetrating readily but not 

 violently ; and not striking injuriously on the membrane covering the drum 

 of the ear. Can these purposes be accomplished, when it is the custom of 

 so many carters and grooms to cut out the hair of the ear so closely and in- 

 dustriously as they do ? The groom who singes it to the root with a candle 

 must be either very ignorant or very brutal. It can scarcely be accomplished 

 without singeing the ear as well as the hair. Many a troublesome sore is 

 occasioned by it ; and many a horse that was perfectly quiet before, rendered 

 difficult to handle or to halter ; and even disposed to be otherwise vicious 

 from a recollection of the pain which he suffered during the absurd and 

 barbarous operation. 



The sound collected by the outer ear, passes through the lower or 

 annular, ring-shaped, cartilage, and through irregularities, which, while 

 they break and modify it, carry it on to another canal, partly cartilaginous, 

 and partly bony, conducting immediately to the internal mechanism of the 

 ear. This canal or passage, is called the external auditory passage, a; and 

 at the base of it is placed, stretching across it, and closing it, a thick and 

 elastic membrane, called the membrane of the drum, h. This membrane 

 is supplied with numerous fibres, from the fifth pair, or sensitive nerve of 

 the head, for it is necessary that it should possess extreme sensibility. 



The mechanism of the ear is so exquisite that we cannot refrain from 

 entering into a minute description of it, although we feel that we are some- 

 what trenching on the comprehensive subject of animal physiology. 



Sound is produced by certain vibrations or undulations communicated 

 to the air, by the concussions or tremblings of things around, and which 

 vibrations spread through the air, and fall upon the ear. The striking of 

 a glass, and the sound of a large bell, are sufficient illustrations of the 

 manner in which sound is propagated by distinct vibrations or waves of 

 the air. These vibrations reach the conch of the ear. From its hollow 

 form and peculiar shape, and the faculty of being directed to every quarter 

 whence the vibrations proceed, they are collected, and condensed, and con- 

 veyed down the outer passage, and fall upon the membrane, h. That 

 membrane, tightly stretched, and elastic, receives the impression made 

 upon it, and vibrates in perfect unison. 



This membrane covers the entrance into a cavity, called the tympanum 

 or drum of the ear, /, from its supposed resemblance to a drum. It is of 

 an irregular shape. Thewalls or sides are composed of bone, lined with a 



