ons.

[29] Mill's Analysis, vol. i. p. 73.

[30] This reasoning of Dr Brown's is founded upon an assumed
analogy between the structure of the optic nerve, and the
structure of the olfactory nerves and other sensitive nerves,
and is completely disproved by the physiological observations of
Treviranus, who has shown that no such analogy exists: that the
ends of the nervous fibres in the retina being elevated into
distinct separate _papillae_, enable us to perceive the
extension, and discriminate the position of visible bodies,
while the nerves of the other senses being less delicately
defined, are not fitted to furnish us with any such perception,
or to aid us in making any such discrimination. See _Mueller's
Physiology, translated by W. Baly, M.D._, vol. ii. pp. 1073,
1074. Although the application of Treviranus's discovery to the
refutation of Dr Brown's reasoning is our own, we may remark, in
justice to an eminent philosopher, that it was Sir William
Hamilton who first directed our attention to the _fact_ as
established by the great physiologist.

But, of course, our main business is with the expression of his own
opinion. In rebutting our charge, he maintains that "the visibility of
angular distance (that is of extension laterally) is assumed, by
implication, as part of Berkeley's doctrine, in _almost_ every chapter
of my book."--(_Letter_, p. 13.) That word _almost_ is a provident
saving clause; for we undertake to show that not only is the very
reverse assumed, by implication, as part of Berkeley's doctrine, in the
_single_ chapter to which we confined our remarks, but that, in another
part of his work, it is expressly avowed as the only alternative by
which, in the author's opinion, Berkeley's consistency can be preserved.

At the outset of his enquiry, Mr Bailey divides his discussion into two
branches: first, Whether objects are originally seen to be external, or
at _any_ distance at all from the sight; and, secondly, Supposing it
admitted that they are seen to be external, or at _some_ distance from
the sight, whether they are all seen in the same plane, or equally near.
It was to the former of these questions that we exclusively confined our
remarks;[31] and it was in reference to it, and to an important argument
evolved by Mr Bailey in the course of its discussion, that we charged
him with fathering on Berkeley the doctrine which he no