are by far the most vivid, as in ordinary cases of reflection a portion
of light is absorbed.

I should be pleased to enter more fully into this branch
of the science of optics, but the bounds to which I am
necessarily limited in a work of this kind will not admit of it.
In the next chapter, however, I shall give a synopsis of Mr. Hunt's
treatise on the "Influence of the Solar Rays on Compound Bodies,
with especial reference to their Photographic application"--
A work which should be in the hands of every Daguerreotypist,
and which I hope soon to see republished in this country.
I will conclude this chapter with a brief statement of the
principles upon which the Photographic art is founded.

SOLAR and Steller light contains three kinds of rays, viz:

1. Colorific, or rays of color.

2. Calorific, or rays of heat.

3. Chemical rays, or those which produce chemical effects.

On the first and third the Photographic principle depends.
In explaining this principle the accompanying wood cuts,
(figs. 3 and 4) will render it more intelligible.

If a pencil of the sun's rays fall upon a prism, it is bent in passing
through the transparent medium; and some rays being more refracted
than others, we procure an elongated image of the luminous beam,
exhibiting three distinct colors, red, yellow and blue, which are