itself was blue glass; but, as this
could not be found, numerous were the expedients proposed by the
friends of the art, who from time to time visited our rooms. At the
suggestion of Professor Mapes (who is ever ready to assist those in
perplexity), a trough of plate glass s, about twenty-eight inches
square in the clear, and from three to four inches thick, was filled
with a solution of ammonia sulphate of copper, and mounted on the frame
as in the sketch, which, for a time, answered extremely well; soon,
however, decomposition of this solution became apparent from the
increased length of time required for a sitting, although to the eye of
an observer, no visible cause for such long sittings could be pointed
out. Professor Mapes being appealed to, suggested that to the above
solution a little acid be added which acted like a charm--shortening
the time for a sitting from six, eight, or ten minutes to that of about
one. Decomposition, however, would go on by the action of light and
heat through the solution. New solutions were tried, when the whole
were finally abandoned as being, too uncertain and troublesome. (The
reflecting apparatus R, was placed upon the stand as in the sketch,
with a wedge for elevating the camera, between it and the table, to
obtain the image properly upon the plate.) A quantity of blue window
glass was next obtained, and holes drilled through the corners of it,
and several sheets were wired together to increase the size, and, when
complete, was suspended from the ceiling in its proper place, and so
arranged that when a person was sitting, this sheet of glass could be
moved to and from, the object of which was to prevent shadows on the
face of the sitter produced from the uneven surface of the glass. This
latter contrivance was used until a perfect plate of glass was procured.

The number of persons desirous of obtaining, their miniatures, induced
many to entertain the idea of establishing themselves in the Art as a
profession, and numerous were the applications for information; many
persons paying for their portraits solely with the view of seeing the
manner of our manipulations, in order that they might obtain
information to carry on likeness-taking as a business.

The reflecting camera being a very troublesome instrument to make, and
difficulties besetting us from every source, but little attention could
be given to teaching others; and, indeed, as the facts seemed to be at
this time, we