is secreted. Now, it is obvious that a very important effect must be produced in these particulars, by the degree in which light is communicated to them, both as regards its intensity and its duration. As long as the plant is in the light, the leaf decomposes carbonic acid, appropriating the carbon to the formation of its own proper juice, and returning the disengaged oxygen into the atmosphere. When light is removed, it has no longer power to imbibe carbon and disengage oxygen; but, on the contrary, it gives back some of the carbon already obtained, and absorbs oxygen, for the purpose of reconverting this into carbonic acid. The simple mention of this fact shows in what a different state a plant must be placed, with regard to its vegetative action, in consequence of the increased and lengthened light of summer. When the nights are longer than the days, the greater part of its existence is spent in reversing the process by which some of its most important properties are obtained. As the day lengthens, it requires longer time to feed on the light, and spends less in the exhausting, but still, to a certain extent, useful process of deple

tion.

In the increased light, then, as well as in the increased heat of the summer months, we find a beautiful adaptation to the peculiar properties of vegetable productions. They are now in a state of growth. In their progress towards maturity, they stand peculiarly in need of powerful excitement and healthy nourishment. This, the Creator has provided for them, not merely in the additional warmth, but in the additional brilliancy, and lengthened influence, of the solar rays. The beneficial effect thus produced will appear, whether we consider the different influence of different seasons in the same country, or compare the vegetation in one climate with that of another. In a gloomy season, when the light of the sun has been much obscured by clouds, this circumstance is not compensated for by the heat of the weather. Vegetable nature puts on a sombre hue, corresponding with the aspect of the atmosphere. All nature seems to droop. The flowers become pale, and hang their heads. Their

III.

3

IX.

fragrance and their beauty decay. The fruits ripen slowly and imperfectly, and their flavor comes not. Herbs, plants, and trees, seem all equally to mourn the absent sun. But let the case be reversed; let the clouds disperse, and the sun shine forth in his strength. Presently all nature regains its loveliness. The colors of the flowers brighten, and their perfume fills the air. The fruit blushes on the trees, and seems to invite the hand of the passer by. The productions of the gardens and the fields are invigorated, and their peculiar properties are heightened and improved. Every thing seems to revive and to rejoice in the genial beam.

The powerful effect of light is not less obvious within the tropics, and in countries bordering on these regions. There the beauty and fragrant scent of the flowers increase in proportion to the brilliancy and clearness of the atmosphere; the taste of edible substances becomes more racy and pungent; and the vegetable produce increases in variety and usefulness. It is on the properties of light, more than on those of heat, that these differences depend, as has been proved by direct experiment.

Here, then, we have a new proof of beneficent contrivance. The source of heat is also the source of light. These two qualities, though differing from each other in essential properties, are yet combined in the sun, and constantly accompany each other by means of this combination, in all the arrangements which constitute weather, becoming more or less intense in relative proportions. We are so accustomed to find light and heat in combination, that it seems to be a kind of violence done to our judgement, to consider them as disunited. They are probably, indeed, properties of the same substance, although one set of these properties is sometimes quiescent, as we have elsewhere observed, while the other is in a state of activity. Let us suppose that they always appeared separately; that the sun, for example, was the source of heat, and the moon the source of light. The earth would still be cheered, every twenty-four hours,

* See 'Winter,' articles on Ignis Fatuus, Phosphorescence, &c.

with the presence of both of these essential qualities, but without correspondence, and without cooperation. The moment that they ceased to coincide, they would cease to be useful. The whole system of the weather, and along with it, of organized matter, would be deranged; vegetable life would cease to be reproduced; and this being the case, animal life would necessarily perish. A much smaller alteration than this, indeed, would produce nearly a similar effect. Suppose that the law were, that light and heat should give out their influence in an inverse, instead of a direct ratio,-that the light was greatest when the heat was most diminished. We should thus have brilliant, but cold suns in winter, and warmth but

gloom in summer. The consequences of such an arrange

ment it might be difficult to trace in all its effects on the complicated machinery of the atmosphere; but that it would be altogether unsalutary, it is easy to perceive. The heat of summer might be sufficient to cherish a pale and feeble vegetation, but the plants would be destitute of a vigorous fibre, the flowers would but languidly expand their petals, and the seeds would not ripen. In a few years, on the supposition of the constitution of plants remaining the same as at present, the powers of reproduction in most of the vegetable kingdoms would cease, and the soil would be left in possession of the few unimportant plants which now flourish in the shade.

There appears to be nothing in the nature of things to render such an arrangement impossible. How comes it, then, that light and heat increase and diminish in the same ratio, or, indeed, that they are combined at all? Or, granting that there is a natural necessity for this combination, how comes it that plants have received such a constitution that the increase of light is as necessary to their perfection as the increase of heat? Only one answer can be given to this question. It is the arrangement of an Intelligent Being. Chance is excluded. The law which connects vegetable life with the actual state of light and heat, must have been imposed by a wise and benevolent Creator.

If it be objected, that I have been speaking only of the

properties of the sun in temperate regions, and that between the tropics a different law prevails; I answer, the arrangement is, in some respects, different, but not opposite. There is a smaller range in the alternations of heat and cold, of brightness and gloom, of night and day; and let it be remarked, that both vegetables and animals are singularly adapted to this peculiar condition. Organized existences are created with properties suitable to the state of the tropical weather, just as others are created for existing and flourishing under the arrangements of a temperate climate. And this, in fact, singularly strengthens our argument. How does it happen that tropical plants possess these properties? It is not from an inherent principle of accommodation to circumstances; for plants possess the property of acclimation, as it is called, only within a very narrow range. Change the arrangement with what caution you may, and the experiment will not succeed. Convey the tropical vegetation to the temperate zone, and that of the temperate zone to the tropics, and no favorable circumstances can prevent them from becoming extinct, when left to the natural agency of the climate. Can this be the effect of chance? Can it be mere accident, that the one set of existences is suited to the one set of conditions, and the other to the other? The reply may be safely left to the common sense of the reader; and here, again, we have a new subject of devout admiration.

FIRST WEEK-THURSDAY.

ELECTRICITY.

THE principle of electricity has been already mentioned as residing in the atmosphere; and as it frequently displays its tremendous powers during the summer months in the thunderstroke, it seems to demand some notice, although its properties have been more distinctly ascertained than its uses. The truth is, that, notwithstanding

the attention of philosophers has been very assiduously turned to this subject of late years, especially since the discoveries of Franklin and Galvani, and many very singular facts have been established in regard to this remarkable agent, there is still so much obscurity attached to the whole subject, that, in the present state of the science, nothing very precise can be stated as to the important functions which it doubtless exercises in the economy of Nature.

That electricity extensively pervades the fluid which surrounds our globe is certain; and it is not less distinctly ascertained that it performs a powerful part in influencing and modifying the changes which take place in the weather, both as relates to warmth and to moisture; but its substance is too subtile, and the laws by which it acts are too singular, to enable us, in the present state of our knowledge, to decide either as to the exact nature or the full extent of its operations. That it is extensively employed in the various modifications which the clouds undergo, may well be believed, since it has been ascertained, by means of Franklin's electric kite, that clouds are sometimes negatively and sometimes positively electrified; and, indeed, the copious falls of rain consequent on a thunder-storm, are themselves a sufficient proof of this influence. It has been supposed, that it is the electric power which preserves moisture in the form of mist or cloud while floating in a state of deposition, and that when this influence is withdrawn, it necessarily falls in the form of rain. If this be the case, as is probable, an agency is assigned to the principle which is both extensive and highly important. Were rain always to be the consequence of the deposition of moisture in the atmosphere, a totally different, and certainly a less salutary result would be produced. There would be no clouds, and the showers would fall almost without warning, suddenly, violently, and frequently. It is probable, too, that rain would fall more partially and unequally than is the case at present, when clouds, once formed, are borne in all directions on the wings of the wind. At all events, we know, that the present