with beauty; where there was deadness, there is animation; where there was taint and corruption, there is health and soundness. The spring is past, and summer reigns. The Sun of Righteousness shines in all his glory, and the soul is buoyant with spiritual life, and teems with fruit.

Yet this progress, though sure, is slow, and frequently retarded. The sun is not yet without clouds, nor the atmosphere free from storms; a sudden cold may still chill; the thunder may raise its terrible voice; the floods may burst forth and overwhelm. The enemy comes: Tares are sown and grow; thorns spring up, and mildew and blight are in the air. It is, at the best, but an earthly summer, though the vivifying influences come from heaven. The harvest, however, approaches. Then the tares shall be separated from the wheat. The tares shall be burned with unquenchable fire; but the wheat shall be gathered into the garner of God.

FIRST WEEK-MONDAY.

INCREASED HEAT.

SUMMER may be said to be the season of growth, as Spring is of reproduction. Those organized existences, which burst into life in the latter season, are either brought to maturity, or, at least, invigorated and expanded in the former, and, in both seasons, the peculiar character of the weather is most wisely adapted for the intended object. We have already had occasion to remark the proofs of Creative design and intelligence, which may be drawn from the adjustment that subsists between the inorganic and the organic worlds, in very many and very striking particulars. The state of the atmosphere, during the progress of the summer months, presents itself as an appropriate subject of consideration, in entering on the study of this season.

I have elsewhere stated the general principles of at

mospheric phenomena,* but what falls under our notice at present, is the change produced in the weather by the advancing year. The sun is now approaching the northern tropic, having, in the month of March, passed from the south to the north of the equator. He is rising high in the heavens, and thus pouring his rays more directly on this part of the earth, which, according to a principle already explained, causes his influence to be móre powerful; and what much adds to this influence, is the greater length of time in which he remains above the horizon. In the depth of winter, we enjoyed his presence little more than seven hours out of the twenty-four. the beginning of summer, this period is increased to upwards of fifteen hours, and in the middle of it, he daily lingers with us two hours longer still. There is thus not only a great direct increase, but a great accumulation of heat.

In

The mode in which this effect is produced, may be shortly mentioned. The rays of the sun, or whatever the influence may be which generates heat, in passing through a perfectly transparent medium, do not increase the temperature of that medium. They seem to require resistance to produce this effect. It is not therefore till they reach the earth, that their power is very sensibly exerted. In striking upon the opaque surface of our globe, they give out their qualities. Light and warmth are produced and reflected. The earth and the atmos

These

phere are thus both subjected to their influence. become heated, the one by conduction, the other by reflection. Now, it is obvious, that while the intensity must be in proportion to the directness with which the globe is struck by the sun's rays, the accumulation must be in proportion to the length of time during which the influence continues. Hence, there is a double cause for the summer's heat, the height to which the luminary rises in the heavens, and the length of the day compared

* Volume on Winter,' article Atmosphere, &c.; and volume on 'Spring,' article Rain, &c.

† [The author speaks of his own country. In the latitude of Boston, the shortest days are nine hours long, wanting six minutes, and the longest days are fifteen hours and six minutes long.-AM. ED.]

with the night. These causes operate in an increasing ratio. Day after day the accumulated heat receives fresh accessions. Every time the sun's influence is repeated, it penetrates deeper below the surface, and is more intensely reflected into the already-heated atmosphere. This effect continues even after the direct solar heat has begun to be diminished; and it is not till several weeks after the sun has begun to take a retrograde motion, that the temperature is at its maximum. In June, the sun reaches his greatest height, and begins to decline, but the heat continues to increase till the middle or end of July.

But there are various circumstances besides warmth, which constitute summer weather. The mechanism of the atmosphere is very complicated, and the adjustments which it requires are exceedingly nice, and, considering merely the nature of the powers employed, we may well add, hazardous. Any change in the relative proportion of one of the principles, is calculated to produce a powerful effect on all the rest, and were there not a regulating power of consummate wisdom, it might be expected that the balance would be overset, and that the most disastrous consequences would ensue. Let us look for a moment at the constituents of the atmosphere, and this will become apparent. The air, which forms the chief part of the atmosphere, is composed of two substances, held together merely by mechanical admixture, which are of very different properties, and which require to continue united in the precise proportion they actually bear to each other, in order to be capable of sustaining animal and vegetable life. Were that proportion destroyed even in a slight degree, the air we breathe would be instantly converted into a deadly poison. Now, it is well worthy of remark, that, although in the functions both of animal and vegetable life, and in the process of combustion, a great and apparently unequal consumption of these two substances takes place, the proportion between them is always maintained, and that notwithstanding any difference of temperature. Heat expands, and cold contracts them, but they are not thus disunited, or

in any way disturbed in their proportions. On the contrary, it is probably in some degree owing to the alternations of heat and cold, which keep up a constant motion in this wonderful fluid, that the necessary balance is maintained.

Another ingredient in the atmosphere is moisture. This is very sensibly acted on by heat. It is the principle of heat which evaporates the moisture from the earth, and causes it to mix with the air, and to float in it, sometimes as an invisible fluid, sometimes in the form of clouds, and which at other times causes it to be precipitated in the form of rain. Now, the remarkable circumstance is, that although heat is the agent in these operations, the change of temperature does not so affect the process as to cause the operations to cease, or very materially to disturb them. Evaporation goes on both at a low and a high temperature, and in both states clouds are formed and rain falls. This is owing to a very peculiar provision, obviously imposed by consummate wisdom. The air is made capable of containing vapor in a certain proportion to its temperature, and it is not till it be saturated that the evaporation from the surface of water ceases, or that deposition takes place. The temperature of the air in winter does not, indeed, admit of the same quantity being held in solution, as in summer, but, up to a certain point, it is equally capable of sustaining it in the one case as in the other. Evaporation, therefore, takes place in very cold weather, even from ice and snow, and the water thus infused into the air is carried up into the higher regions, till it reaches the point where the temperature is such as to correspond with the quantity of moisture. Precisely the same process takes place in summer, with this difference, that the evaporation is much more abundant, and the air, owing to its increased temperature, is capable of containing a far greater quantity in solution. Again, the point of deposition is regulated by a similar law, with a similar difference. Deposition does not take place either in winter or summer, till the air is more than saturated; but this effect is produced at very different temperatures, according to the quantity actually

held in solution, so that a very slight degree of cold will form clouds and cause rain in summer, compared with what is necessary to occasion the same phenomena in winter. Hence the processes of evaporation and deposition are made, by this very peculiar law, always to bear a relation to the actual temperature of the season, and such a balance is kept up between these processes, as is admirably suited to the wants of vegetable and animal life.

I may add to all this the properties of the atmosphere, by means of which it is made the vehicle of light and sound, and the means of respiration. The changes which the air undergoes by the operation of heat and cold, might easily be supposed, and might even, perhaps, reasoning without the aid of experience, be expected to produce a material alteration on such properties. But although these changes are so considerable in different seasons, and in different climates, we do not find that the laws either of vision or of acoustics, are in any material degree affected by them, or that the action of the lungs, either in man or the lower animals, is impeded or deranged.

In attending to the complicated nature of the atmosphere, and the various important functions it has to perform, and in considering the diversified modifications it must necessarily undergo by the alteration of its temperature, both in the various latitudes of the globe, and in the different seasons of the year, it does seem impossible to doubt that the uniformity of its properties, and of its salutary influences under all these modifications, has been provided for, by what Whewell, considering that subject in a more extended view, justly calls "a most refined, far-seeing, and far-ruling contrivance." So many opposing forces, and the mingling of such subtile and fearfully active elements, appear, in the most quiescent state, to require amazing prospective skill for their regulation and control; and when we find them, even under the influence of extensive changes, still harmoniously combining their powers for the general good, we cannot but perceive that all this could not be effected but by the