Observer. Constant Error. Average Deviation. Mean Variation. _A_ (50) + 7.75 20.07 19.45 _C_ " + 14.41 25.05 2.94 _D_ " + 14.42 34.54 29.16 _E_ " +108.97 108.97 23.13 _F_ " - 5.12 23.00 2.02 _G_ " + 20.72 34.80 10.23 _H_ " + 35.07 53.60 33.95 _I_ " + 25.52 30.68 22.49 _K_ " - 8.50 40.65 21.07 Average: + 23.69 41.26 17.16 The point at which the eyes rest when seeking the plane of the horizon in total darkness is above its actual position, the positive displacement involved being of relatively large amount. In addition to the removal of the whole diversified visual field there has now been eliminated the final point of regard toward which, in the preceding set of experiments, the sight was strained; and the factor of refined visual adjustment ceases longer to play a part in the phenomenon. The result of this release is manifested in a tendency of the eyes to turn unconsciously upward. This is their natural position when closed in sleep. But this upward roll is not an uncomplicated movement. There takes place at the same time a relaxation of binocular convergence, which in sleep may be replaced by a slight divergence. This tendency of the axes of vision to diverge as the eyes are raised is undoubtedly connected biologically with the distribution of distances in the higher and lower parts of the field of vision, of which mention has already been made. Its persistence is taken advantage of in the artificial device of assisting the process of stereoscopic vision without instruments by holding the figures to be viewed slightly above the primary position, so that the eyes must be raised in order to look at them and their convergence thereby decreased. It is by the concomitance of these two variables that the phenomena of both this and the preceding series of experiments are to be explained. In the present case the elimination of a fixed point of regard is followed by a release of the mechanism of convergence, with a consequent approximation to parallelism in the axes of vision and its concomitant elevation of the line of sight.