202 THE FARMER AT HOME. 



very fine and good for lambs and calves, but has not the nourishment 

 which the more natured plant possesses. 



HEAD. In Anatomy. The head, besides possessing muscular 

 parts and integuments in common with the rest of the body, is the seat 

 of the organs of the external senses, and of the bony cavity in which 

 the brain is placed. This variety of structures and of the functions 

 which are performed by them, renders the head liable to many dis- 

 eases, of which some affect the skin, muscles, and cellular texture, 

 others the organs of sense, and others the brain and internal parts of 

 the skull. The head is liable to all the varieties of external injury, 

 of wounds of the scalp, and fractures of the skull ; the organs of sense, 

 to their peculiar maladies ; and the brain and the internal parts to 

 very many diseases. In an important work with which the profession 

 has been favored by Dr. Abercrombie, he classes the diseases of the 

 internal parts of the head under the inflammatory, the apoplectic, and 

 the organic. 



HEARING. The ear is the organ of hearing. In man it con- 

 sists of an external ear, and an internal bony cavity with numerous 

 circular and winding passages, by which the vibrations of the air are 

 collected and concentrated, and by a peculiar mechanism conveyed to 

 the auditory nerves. The ear is supplied with peculiar glands, which 

 secrete an unctuous substance, called the wax of the ear. The internal 

 auditory passage proceeds in a spiral direction to the tympanum or 

 drum of the ear, which forms a complete partition between this pas- 

 sage and the internal cavities. Beyond the tympanum is a hemi- 

 spherical cavity which leads to the fauces, or opening at the back of 

 the mouth. This opening is of a trumpet form. The inner cavity, 

 including the winding passage, is aptly called the labyrinth of the 

 ear. The sense of hearing is, perhaps, still more important than that 

 of seeing ; but as we can have no just conception of the real state of 

 social existence without either of these senses, it is idle to speculate on 

 such comparisons. 



HEAT. Heat is the well known sensation which we perceive on 

 touching any substance whose temperature is superior to that of the 

 human body. Chemists have agreed to call the matter of heat caloric, 

 in order to distinguish it from the sensation which it produces. Caloric 

 has a tendency to diffuse itself equally among substances that come 

 in contact with it. If the hand be put upon a hot body, part of the 

 caloric leaves the hot body, and enters the hand ; this produces the 

 sensation of heat. On the contrary, if the hand be put upon a cold 

 body, part of the caloric contained in the hand, leaves the hand to 

 unite with the cold body : this produces the sensation of cold. If you 

 pour warm water into one basin, cold water into a second, and a mix- 

 ture of hot and cold water into a third ; then put one hand into the 

 cold water, and the other into the warm; for two minutes, and after 

 that put both hands into the luke-warm water, to the one hand it will 



