"An evening red, and morning gray,
Will set the traveler on his way;

But an evening gray, and a morning red,

Will pour down rain on the traveler's head."

The "rainbow," that so frequently adorns and glads the clouded watery heavens, in full display of gorgeouscolored zones of first-created light, as "the token of the covenant between God and man, that the waters shall no more become a flood to destroy all flesh," must be esteemed as the most beautiful and magnificent atmospheric phenomenon that we behold throughout the Four Seasons of the revolving year.

This phenomenon, however, does not admit of explanation through the medium of Chemistry; its interpretation belongs to the very highest departments of the science of Optics, and there probably we only know it in part; but even such part, if it could be here admitted, would more than occupy the remaining limits that are assigned for the actual chemical phenomena of Autumn and Winter.

But we are inevitably led for a few moments to quit the direct province of Chemistry, and trespass upon that of Optics, for unfolding the probable physical cause of the rainbow, in concise and intelligible terms.

The rainbow invariably appears in that part of the heavens which during the day is directly opposite to the sun, and whilst rain is falling between the dark clouds in the one quarter, and the solar beams in the other; these, under most circumstances, impinging upon pellucid drops of water, will either directly pass through them in right lines, or, if refracted from such course, they will, upon emerging from the drops, immediately resume it, and pass onward as colorless light.

Under certain natural conditions, which merely to facilitate our inquiry may for the moment be called extraordinary, the solar rays impinging upon drops of water, will not only pass through them, or be simply refracted, as above, but upon emerging from the drops, a portion of the rays will continue to pass onward as colorless light after ordinary refraction; whilst another portion deviates from such path, and is further refracted, or broken, into seven extraordinary-colored rays, or prismatic rays, as mentioned at page 36 of the Introductory Chapter.

This extraordinary or colored refraction or analysis of solar light, is frequently presented by drops of morning dew, but in greater perfection by drops of rain, in falling through the atmosphere, between a dark cloud and the brilliant sun, the rays of which, entering and emerging from successive drops, are refracted into Violet light, which departs farthest from the path that the unaltered rays would have pursued, and into Red light, which keeps nearest the path that the unaltered rays would have pursued; thus the external and the internal fringes of the rainbow are formed, and they include within their zones the remaining colored rays in the order of their inherent refrangibility, the Indigo, Blue, and Green, being nearest the Violet, whilst the Yellow and Orange are nearest the Red; thus presenting a perfect rainbow of the seven colors of analyzed light.

Or, in more technical terms, the Violet, Indigo, Blue, and Green rays, are the most refrangible, whilst the Yellow, Orange, and Red, are the least refrangible rays of solar light; the rainbow, therefore, is said to present a magnificent natural example of its analysis; for the colored rays cannot be divided into others.

When a single and perfect rainbow appears, its interior fringe is Red, and its exterior fringe is Violet; but a "double rainbow" is most frequent; a phenomenon, that is, of one bow within another; and then not only are the colors of the inner and smaller, or Primary bow, more vivid than those of the outer and larger, or Secondary bow, but they are exactly in the reverse order, the interior fringe of the inner bow being Violet, and its exterior fringe being Red.

The form of the "double rainbow" the artist has successfully represented in the above engraving, the dark shading of the bows denoting their respective fringes of violet light, as the employment of surfaces to reflect individual colors is impracticable in this department of art; indeed, when we consider that the effect of an engraving depends upon the total reflection of one portion of colorless light, by the surface of the paper, and the total absorption of another portion by the surface of the ink, it becomes extraordinary that simple engravings should convey to the eye any correct notion of the appearances of surrounding objects.

The following ancient and popular proverb concern

ing the "rainbow," affords one more example of a refined physical truth appearing in plain homely guise:

"A rainbow in the morning, is the shepherd's warning,
A rainbow at night, is the shepherd's delight."

"This old proverb is generally correct, as a rainbow can only occur when the clouds containing or depositing the rain are opposite to the sun; and in the evening the rainbow is in the East; and in the morning in the West; and as our heavy rains in this climate are usually brought by the westerly wind, a rainbow in the West indicates that the bad weather is on the road by the wind to us; whereas the rainbow in the East proves that the rain in the clouds is passing from us."

"As an indication of wet weather approaching, nothing is more certain than a halo round the moon, which is produced by the precipitated water, and the larger the circle, the nearer the clouds, and consequently the more ready to fall."

All things demand equal attention from him who truly loves and desires knowledge; thus the foregoing explanation of the homely proverb emanated from the most enlightened philosopher that ever devoted his talents to the fascinating science of Chemistry.

Educated in strict accordance with the inflexible doctrines of "Inductive Philosophy," constantly inferring and collecting general results, general facts, and laws, from a number of particular instances carefully established on actual Experimental evidence, this philosopher proved the utility of Chemistry when judiciously applied towards increasing the resources, and adding to the welfare of man ;-demonstrated its importance as a medium for interpreting the wonders of natural phenomena ;—

concentrated all its varied rays, by the mirror of truth, into one effulgent star of light, for the moral and intellectual guidance of man, towards "The First Author of Beauty who hath created them all.”

God, for the fulfillment of His inscrutable purposes, has been pleased to take the spirit of this true philosopher to a better and more elevated sphere than the world that it was permitted for a few years to enlighten and adorn; the voice that once poured forth fervid eloquence regarding the wonders of the Creation, is hushed, and the hand that demonstrated them, is closed in the silent, cold grave.

But those words of fervor, and works of skill, are faithfully remembered, and zealously guarded by his disciples who are yet permitted to remain; and as they follow at a vast distance the footsteps of their master, they endeavor, as he did, to keep the laborious yet certain path that is permanently illuminated by true experiment, and to shun the seductive uncertain mazes that are capriciously lighted by the false fires of theory and hypothesis.

In cases of doubt and indecision, reliance may always be placed upon the light of experiment, because its rays emanate from the rock of truth; theory and hypothesis "impose upon the imagination like the 'mirage' of the Egyptian sands, but like this illusion they must pass away; they may present to the eye a magnificence as seducing as the 'fata morgana' oftentimes witnessed on the coast of Calabria, in which the most beautiful landscapes, crowned with picturesque villages, superb palaces, and massy towers, seem to possess a real existence; all is but an aërial phantom; the enchanted scene changes with the least shifting of the light or the