_A Stereoscopic Note._--I possess a small volume entitled _A Disquisition
about the Final Causes of Natural Things_, by T. H., B.B., Fellow of the
Royal Society, 1688. "To which are subjoined, by way of Appendix, some
uncommon observations about vitiated sight." In this strange appendix, one
of the uncommon observations is worth the notice of your correspondents who
write on stereoscopic subjects. I give you an extract from it:
"It has been of late the opinion of very learned men, that though both our
eyes are open, and turned towards an object, yet 'tis but one of them at a
time that is effectually employed in giving us the representation of it:
which opinion, in this place where I am writing but observations, it were
not proper to discuss, especially because what is suppos'd to be observed
will not always uniformly happen, but may vary in particular persons
according to their several customs, and the constitution of their eyes: for
I have, by an experiment purposely made, several times found, that my two
eyes together see an object in another situation than either of them apart
would do." And in giving instances for and against binocular vision, the
author says: "A yet more considerable instance of such mistakes I
afterwards had from a noble person, who, having in a fight, where he play'd
the _hero_, had one of his eyes strangely shot out by a musquet bullet,
that came out at his mouth, answered me, that not only he could not well
pour drink out of one vessel into another, but had broken many glasses by
letting them fall out of his hand, when he thought he had put them into
another's, or set them down upon a table." The whole book is a very curious
one, and I should be obliged if the Editor of "N. & Q." could tell me who
T. H. was?[5]