sitive paper
beneath confesses its weakness, and betrays it by growing dark just in
proportion to the glare that strikes upon it. So, too, we have only
to turn the glass before laying it on the paper, and we bring all the
natural relations of the object delineated back again,--its right to the
right of the picture, its left to the picture's left.

On examining the glass negative by transmitted light with a power of a
hundred diameters, we observe minute granules, whether crystalline or
not we cannot say, very similar to those described in the account of
the daguerreotype. But now their effect is reversed. Being opaque, they
darken the glass wherever they are accumulated, just as the snow darkens
our skylights. Where these particles are drifted, therefore, we have our
shadows, and where they are thinly scattered, our lights. On examining
the paper photographs, we have found no distinct granules, but diffused
stains of deeper or lighter shades.

Such is the sun-picture, in the form in which we now most commonly meet
it,--for the daguerreotype, perfect and cheap as it is, and admirably
adapted for miniatures, has almost disappeared from the field of
landscape, still life, architecture, and _genre_ painting, to make room
for the photograph. Mr. Whipple tells us that even now he takes a much
greater number of miniature portraits on metal than on paper; and yet,
except occasionally a statue, it is rare to see anything besides
a portrait shown in a daguerreotype. But the greatest number of
sun-pictures we see are the photographs which are intended to be looked
at with the aid of the instrument we are next to describe, and to the
stimulus of which the recent vast extension of photographic copies of
Nature and Art is mainly owing.

3. THE STEREOSCOPE.--This instrument was invented by Professor
Wheatstone, and first described by him in 1838. It was only a year after
this that M. Daguerre made known his discovery in Paris; and almost
at the same time Mr. Fox Talbot sent his communication to the Royal
Society, giving an account of his method of obtaining pictures on paper
by the action of light. Iodine was discovered in 1811, bromine in 1826,
chloroform in 1831, gun-cotton, from which collodion is made, in 1846,
the electro-plating process about the same time with photography; "all
things, great and small, working together to produce what seemed at
first as delightful, but as fabulous, as Aladdin's ring, which is now as
little s