miles away, and at night we see the stars millions of miles
away; but then, if confined to the long range, we should be strangers at
home, and never get within a mile of any acquaintance. Now, how to
combine these two powers, of seeing near objects and distant ones with
the same eye, is the problem which the Maker of the eye had to solve.
Let us look how man tried to solve it. A magnifying lens will collect
the rays from any distant object, and convey them to a point called the
focus. Then suppose we put this glass in the tube of an opera-glass, or
pocket spy-glass, and look through the eye-hole and the concave lens,
properly adjusted, in front of it, we shall see the image of the object
considerably magnified. But suppose the object draws very near, we see
nothing distinctly; for the rays reflected from it, which were nearly
parallel while it was at a distance, are no longer so when it comes
near, but scatter in all directions, and those which fall on the lens
are collected at a point much nearer to the lens than before, and the
eye-glass must be pushed forward to that focus. Accordingly, you know
that the spy-glass is made to slide back and forward, and the telescope
has a screw to lengthen or shorten the tube according to the distance of
the objects observed. Another way of meeting the case would be by taking
out the lens, and putting in one of less magnifying power, a flatter
lens, for the nearer object. Now, at first sight, it would seem a very
inconvenient thing to have eyes drawing out and in several inches like
spy-glasses, and still more inconvenient to have twenty or thirty pairs
of eyes, and to need to take out our eyes, and put in a new set twenty
times a day. The ingenuity of man has been at work hundreds of years to
discover some other method of adapting an optical instrument to long and
short range, but without success. Now, the Former of the eye knew the
properties of light and the properties of lenses before the first eye
was made; he knew the mode of adjusting them for any distance, from the
thousands of millions of miles between the eye and the star, to the
half-inch distance of the mote in the sunbeam; and he had not only
availed himself of both the principles which opticians discovered, but
has executed his work with an infinite perfection which bungling men may
admire, but can never imitate. The sclerotic coat of the eye, and the
choroid which lies next it are full of muscles which, by their
contract