ction of our sight, we are induced
_voluntarily_ to attend to them; and then these apparent motions become
succeeded by sensation; and thus the other parts of the trains of
irritative ideas, or irritative muscular motions, become disordered, as
explained above. In these cases of slight vertigo I have always promised my
patients, that they would get free from it in two or three months, as they
should acquire the habit of balancing their bodies by less distinct
objects, and have seldom been mistaken in my prognostic.

There is an auditory vertigo, which is called a noise in the head,
explained in No. 7. of this section, which also is very liable to affect
people in the advance of life, and is owing to their hearing less perfectly
than before. This is sometimes called a ringing, and sometimes a singing,
or buzzing, in the ears, and is occasioned by our first experiencing a
disagreeable sensation from our not being able distinctly to hear the
sounds, we used formerly to hear distinctly. And this disagreeable
sensation excites desire and consequent volition; and when we voluntarily
attend to small indistinct sounds, even the whispering of the air in a
room, and the pulsations of the arteries of the ear are succeeded by
sensation; which minute sounds ought only to have produced irritative
sensual motions, or unperceived ideas. See Section XVII. 3. 6. These
patients after a while lose this auditory vertigo, by acquiring a new habit
of not attending voluntarily to these indistinct sounds, but contenting
themselves with the less accuracy of their sense of hearing.

Another kind of vertigo begins with the disordered action of some
irritative muscular motions, as those of the stomach from intoxication, or
from emetics; or those of the ureter, from the stimulus of a stone lodged
in it; and it is probable, that the disordered motions of some of the great
congeries of glands, as of those which form the liver, or of the intestinal
canal, may occasion vertigo in consequence of their motions being
associated or catenated with the great circles of irritative motions; and
from hence it appears, that the means of cure must be adapted to the cause.

To prevent sea-sickness it is probable, that the habit of swinging for a
week or two before going on shipboard might be of service. For the vertigo
from failure of sight, spectacles may be used. For the auditory vertigo,
aether may be dropt into the ear to stimulate the part, or to dissolve
ear