fire during night in a spacious plain, where all is gloom and darkness around. It would suddenly burst on our view in the eastern horizon, in the morning, and would not change its aspect in the least, during its course through the heavens, till it suddenly disappeared in the western sky. The objects immediately around us would be partially visible; but the rays of the sun which fell on distant objects would be for ever lost in the expanse of the heavens; and when we turned our back to the sun, nothing would present itself, but an abyss of darkness, and the whole horizon involved in a dismal gloom. The number of objects in the heavens would, indeed, be augmented, for the stars would shine through a canopy as black as ebony, even when the sun was above the horizon; but all the gay colouring of the terrestrial landscape, which now delights the eye and the imagination, would be for ever veiled from the inhabitants of the world. In such a state of things, it would be always night; and the difference between such a night and that which we now enjoy, would be, that the celestial orbs, instead of being grounded on a beautiful azure sky, would appear on a black canopy, like so many white points on a dismal mourning carpet.

But the Almighty, whose arrangements have all a respect to the happiness of his creatures, has enveloped our globe with an atmosphere, and has endowed it with a capacity of reflecting and refracting the rays of light in all directions.

This atmosphere, too, is charged with innumerable myriads of watery particles, exhaled by evaporation from every region of the sea and land. In the serenest days of summer, when no clouds nor vapours are to be seen, these rarefied particles of water, which are imperceptible to the keenest eye, fill the whole sphere of the atmosphere around us, both above and below the region of the clouds. It is among these rarefied waters in the higher regions of the air that the rays of light reflected from the surface of the land meet, and are again reflected in every direction to the earth; and hence is produced that beautiful azure colour which distinguishes the aspect of the heavens, This azure is sometimes lighter, according to the quantity of rays which enter the atmosphere, and sometimes darker, when the absence of the twilight heightens the blue of the celestial concave, by means of that black and void space which lies beyond the limits of the atmosphere. In corroboration of these remarks, it may be noticed, that the higher we ascend above the surface of the earth, the darker does the sky appear. And hence all travellers affirm, that, on the tops of lofty mountains, it sometimes appears as black as ebony, which causes the milky way to appear like a pure flame shot across the heavens, and the stars to shine with a greater brightness, and to appear far more numerous than in the plains below.

11. The atmosphere is the cause of the morning and evening twilight. We all know

that the day is gradually ushered in after the darkness of the night. More than an hour before the rising of the sun, in this part of the world, a streak of light appears in the eastern horizon. This light increases in brilliancy every moment the landscape of the earth, which had been previously covered with a mantle of blackness, appears gradually to emerge from an abyss of darkness, like the light at the first creation-the circle of the horizon becomes inflamed with a bright vermilion-the mountain tops are tinged with purple; and at length appears the most beautiful and sublime object in nature, the sun rising in his might and glory. And, when this luminary has described the circuit of the heavens, and passed the verge of the western horizon, darkness does not come on instantaneously, but by slow and imperceptible degrees, so as to warn us to prepare for its approach. The season of twilight, particularly that of a summer evening, is perhaps one of the most agreeable and interesting periods of the day. How many delightful walks and excursions-how many cheerful and solemn musings-how many endearing intercourses of love and friendship does it recall to our recollection, when we strolled along the solitary walks, or reclined in the bower of friendship, till the rising moon and the twinkling stars called us to our nightly repose!

Now, all such pleasures and advantages derived from the twilight, are owing to the agency of the atmosphere. When the sun

approaches in the morning within eighteen degrees of the horizon, his rays strike obliquely on the higher parts of the atmosphere, and, instead of passing directly forward, they are refracted, or bent a little downwards, and thus descend by inflection to the earth. In this way we reap the benefit of those rays which would otherwise have been totally lost, and enjoy the light of day for a considerable time before the sun reaches the horizon. It is owing to the same cause that the sun is visible several minutes before he is actually above the horizon in the morning, and after his setting in the evening. This increases the length of every day, about 6 minutes at an average, which amounts to 3 equinoctial days in a year, and nearly a whole year's sunshine in the course of a century. And, if we reckon an hour and a half of twilight in the morning and as much in the evening, at an average, through the different seasons, we have more than ninety equinoctial days of twilight throughout the year. This is a circumstance of the utmost importance to those who inhabit the polar regions; in consequence of which, the inhabitants of NovaŻembla and of Greenland enjoy the direct light of the sun for thirty-two days while he is under the horizon, besides the long twilight which precedes his rising, and continues after his descent below the horizon. But what would be the consequences if we had no twilight? Not only should we be deprived of the advantages now stated, but subjected to many incon

veniences and dangers. Should the day break in upon us all at once in meridian brightness, immediately after the dark shades of night, our eyes would be dazzled, and in danger of being blinded by its excessive splendour. Should the night rush on in the same precipitate manner, and hurry us in a moment from the splendours of day to the horrors of midnight, it would strike the living world with amazement. The traveller would be arrested in the midst of his journey, and bewildered with terror; and if the sky were then covered with clouds, the darkness would be so thick and black, that not the least glimmering ray would strike across the universal gloom, nor a single object be perceived, even within the distance of a foot. Man would then appear as if he were placed without an object near him, in the midst of infinite space

"Dark as was chaos, ere the infant sun Was rolled together, or had tried his beams Athwart the gloom profound."

These arrangements, then, by which light is reflected over the face of nature, and twilight is produced, evidently show the wisdom and intelligence of the Almighty Creator, and his benevolent regards to his sensitive and intelligent offspring. A few small bubbles of air and water appear very insignificant to the eye of man. But in the hand of the Almighty they work wonders of love and beneficence. He has distributed them over our heads in every direction with so much caution and skill, in