efracting (bending) power, peculiar
to itself. These rays always hold the same relation to each other, as
may be seen by comparing every spectrum or rainbow; there is never any
confusion or misplacement.

There are various other means of decomposing {134} white light besides
the prism, of which one of the principal and most interesting to the
Daguerreotypist is by reflection from colored bodies. If a beam of
white light falls upon a white surface, it is reflected without change;
but if it falls upon a red surface, only the red ray is reflected: so
also with yellow and other colors. The ray which is reflected
corresponds with the color of the object. It is this reflected
decomposed light which prevents the beautifully-colored image we see
upon the ground glass in our cameras.

[Illustration: Fig. 2 (amdg_2.gif)]

A sunbeam may be capable of three divisions--LIGHT, HEAT, and ACTINISM;
the last causes all the chemical changes, and is the acting power upon
surfaces prepared to receive the photographic image. The accompanying
illustration, Fig. 2, will readily bring to the mind of the reader the
relation of these one to another, and their intensities in the
different parts of a decomposed sunbeam.

The various points of the solar spectrum are represented in the order
in which they occur between A, and B, this exhibits the limits of the
Newtonian spectrum, corresponding with Fig. 1. Sir John Herschel and
Seebeck have shown that there exists, beyond the violet, a faint violet
light, or rather a lavender to b, to which gradually becomes colorless;
similarly, red light exists beyond the assigned limits of the red ray
to a. The greatest amount of actinic power is shown at E opposite the
violet; hence this color "exerts" the greatest amount of influence in
the formation of the photographic image.

(Blue paper and blue color have been somewhat extensively used by our
Daguerreotype operators in their operating rooms and skylights, in
order to facilitate the operation in the camera. I fancy, however,
that this plan cannot be productive of as much good as thought by some,
from the fact, that the light falling upon the subject, and then
reflected into the camera, is, coming through colorless glass, not
affected by such rays as may be reflected from the walls of the
operating room; and even if it were so, I conceive that it would be
injurious, by destroying the harmony of shadows which might otherwise
occur.) The greatest