In the course of these experiments Dr. Wells observes, that the
sympathy between the eyes, which is in general considered as sympathy of the iris, is in fact sympathy of the retina; for when the
pupil of one eye is dilated by belladonna, the pupil of the other becomes so much the more contracted, in consequence of the greater
light which the enlarged pupil admits.
He remarks, also, that though he has lost, in great measure, the power of adaptation, he has in no degree lost any command of the external muscles, but can make the optic axes meet at any short distance from his face, to which he could formerly make them converge. So also, while Dr. Cutting's eyes were under the influence of belladonna, the powers of the external muscles remained unimpaired; whence it appears, that the powcr of adapting the eye to difi'erent distances is not dependent on the external muscles, but rather to be referred to the crystalline lens, although the muscularity of that organ does not appear to Dr. Wells to be by any-means established.
Sir Isaac Newton, who first considered the figure of the earth and planets, confined his view to the supposition of their having been originally in a fluid state; and he conceived them to retain the same figure which they assumed in their prirm'tive condition; and those mathematicians who succeeded him in the same path of inquiry have seldom ventured beyond this limited hypothesis, and have shown, that when a body composed of one uniform fluid revolves about its axis, or even if it consists of several fluids of difi'erent densities, its parts will be in equilibrium, and it will preserve its figure when it has the form of an elliptic spheroid of revolution oblate at the poles.
But though the supposition of original fluidity of the mass simplifies the investigation, it does not seem to be warranted by what we see of the surface ; for in that case, Mr. Ivory observes, the arrangement of all the heterogeneous matters would have been according to their densities; those least dense occupying the surface with gradual increase of density to the centre; whereas, on the contrary, nothing can be more irregular than the density of such solid parts of the earth as come under our observation. and the elevation of continents above the level of the sea, as well as the depths of the different channels which contain the waters of the ocean.
Moreover, according to the latest and best observations made for the express purpose of determining the figure of the earth, it :does not appear to be of any regular elliptic form.
Since the hypothesis of Newton is, therefore, not consonant to observation, it became necessary to consider the subject in a more
