set of muscles. It follows that when the eye is rotated in the
contrary direction the condition of equilibrium appears sooner than in
normal vision. In the case of both observers the subjective horizon
was located higher when judgment was made after keeping the eyes
raised, and lower when the line of sight had been depressed. In the
case of only one observer was a quantitative estimation of the error
made, as follows: With preliminary raising of the eyes the location
was +36'.4; with preliminary lowering, -11'.4.

When the illuminated button is exposed in a darkened room and is
fixated by the observer, it undergoes a variety of changes in apparent
position due to unconscious shifting of the point of regard, the
change in local relations of the retinal stimulation being erroneously
attributed to movements in the object. These movements were not of
frequent enough occurrence to form the basis of conclusions as to the
position at which the eyes tended to come to a state of rest. The
number reported was forty-two, and the movement observed was rather a
wandering than an approximation toward a definite position of
equilibrium. The spot very rarely presented the appearance of sidewise
floating, but this may have been the result of a preconception on the
part of the observer rather than an indication of a lessened liability
to movements in a horizontal plane. Objective movements in the latter
direction the observer knew to be impossible, while vertical
displacements were expected. Any violent movement of the head or eyes
dispelled the impression of floating at once. The phenomenon appeared
only when the illuminated spot had been fixated for an appreciable
period of time. Its occurrence appears to be due to a fatigue process
in consequence of which the mechanism becomes insensible to slight
changes resulting from releases among the tensions upon which constant
fixation depends. When the insensitiveness of fatigue is avoided by a