Two essays: one upon single vision with two eyes; the other on dew / A letter to the Right Hon. Lloyd, Lord Kenyon [on the case of Dr. Stanger], and an account of a female of the white race of mankind, part of whose skin resembles that of a negro; with some observations on the causes of the differences in colour and form between the white and negro races of men. By the late William Charles Wells ... With a memoir of his life, written by himself.

  • Wells, William Charles, 1757-1817.
Date:
1818
Catalogue details

Licence: Public Domain Mark

Credit: Two essays: one upon single vision with two eyes; the other on dew / A letter to the Right Hon. Lloyd, Lord Kenyon [on the case of Dr. Stanger], and an account of a female of the white race of mankind, part of whose skin resembles that of a negro; with some observations on the causes of the differences in colour and form between the white and negro races of men. By the late William Charles Wells ... With a memoir of his life, written by himself. Source: Wellcome Collection.

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    existence of which it is impossible, from the nature of the parts, either to demonstrate, or to refute by experiments; and that no one of them, though admitted to be true, is yet suf- ficientsto explain the phenomena on account of which it was framed. The opinions of the second class being built, as their authors think, upon experiments and observations, both allow and demand a more accurate investigation. I shall proceed, there- fore, to examine such of them as | am acquainted with, beginning with that of Aguilonius; and what I shall observe concerning it will apply also to those of Dechales and Dr. Porterfield, who have done little more than copy what he has said. . If a line be drawn through the point of the mutual intersection of the optic axes, parallel to the interval between the eyes, Aguilonius calls it, from its office, the horopter; and if through this line, a plane be made to pass at right angles to that of the optic axes, he names it the plane of the horopter. After defining these terms, he asserts, that, by a law of our constitution, all bodies which we see with one glance or look, whatever are their real places, appear to each eye to be situated in this plane. And if this be granted to him, he easily and satisfactorily shows, why some should be seen _B2