m the deception of
the sense of touch.

In this vertigo from gyration, both of the sense of sight, and of the sense
of touch, the primary link of the associated irritative motions is
increased in energy, and the secondary ones are increased at first by
direct sympathy; but after a time they become decreased by reverse sympathy
with the primary link, owing to the exhaustion of sensorial power in
general, or to the power of association in particular; because in the last
case, either pleasurable or painful sensation has been introduced between
the links of a train of irritative motions, and has dissevered, or much
enfeebled them.

Dr. Smyth, in his Essay on Swinging in Pulmonary Consumption, has observed,
that swinging makes the pulse slower. Dr. Ewart of Bath confirmed this
observation both on himself and on Col. Cathcart, who was then hectic, and
that even on shipboard, where some degree of vertigo might be supposed
previously to exist. Dr. Currie of Liverpool not only confirmed this
observation frequently on himself, when he was also phthisical, but found
that equitation had a similar effect on him, uniformly retarding his pulse.
This curious circumstance cannot arise from the general effect of exercise,
or fatigue, as in those cases the pulse becomes weaker and quicker; it must
therefore be ascribed to a degree of vertigo, which attends all those modes
of motion, which we are not perpetually accustomed to.

Dr. Currie has further observed, that "in cases of great debility the
voluntary muscular exertion requisite in a swing produces weariness, that
is, increases debility; and that in such instances he had frequently
noticed, that the diminution of the frequency of the pulse did not take
place, but the contrary." These circumstances may thus be accounted for.

The links of association, which are effected in the vertigo occasioned by
unusual motion, are the irritative motions of the sense of vision, those of
the stomach, and those of the heart and arteries. When the irritative ideas
of vision are exerted with greater energy at the beginning of vertigo, a
degree of sensation is excited, which is of the pleasurable kind, as above
mentioned; whence the associated trains of irritative motions of the
stomach, and heart, and arteries, act at first with greater energy, both by
direct sympathy; and by the additional sensorial power of sensation. Whence
the pulse of a consumptive patient becomes stronger and consequently
slowe