a sphere whose surface is very unequally heated, like the present, and whose temperature decreases rapidly from the equator to the poles, lateral currents of air and vapour would ensue, with a condensation of moisture in the form of rain-drops, more or less copious, according to the extent of evaporation in the equatorial regions, and the increasing coldness of the extra-tropical. The ancient world possessed a middle constitution between these two extremes. Its superficial temperature was not very unequable from pole to pole, and its expanse of humid surface was less relative to that of its dry land. Thus the causes of atmospheric commotion were fewer and feebler; and the phenomenon of rain must have been very rare, except on some insular circumpolar coasts. The exhalations from the tepid seas would diffuse abundance of aqueous nourishment to the cactuses, palms, and cycadeoidea of its glowing plains.

Immediately after the flood, however, the seasoaked lands would send up universal exhalations round the chilly globe; whence showers and rainbows would become for some time at least, almost daily appearances.

This conclusion of physical research, coincides well with our ancient history of the new-drained earth. "And God said, This is the token of the covenant which I make between me and you, and every living creature, that is with you for perpetual generations: I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. And it shall come to pass when I bring a cloud over the earth, that the bow shall be seen in the

cloud.

RAINBOWS THE RESULT OF THE DELUGE.

601

And the waters shall no more become a flood to destroy all flesh."-Genesis ix. The ark preserved eight intelligent witnesses, come to mature age, of antediluvian skies and seasons. Had a shower of rain been as common before the flood as it was after it, then the rainbow being a necessary result of the refraction and reflection of the sunbeams by the sheet of falling drops, must have been often seen by the family of Noah, in the land of their birth, and could not therefore be now hailed by them as an infallible seal of a peculiar covenant, graciously bestowed by their reconciled Ruler. He had just appeared in an awful light; as the inexorable judge of their guilty compatriots. Anxiously might they lift their eyes to heaven for some new token to inspire confidence in the stability of the new order of nature; to encourage them to diligence in their enjoined task of replenishing the earth.

It is therefore evident, both from the emphatic words in which the meteoric ensign of heaven's favour is announced, as well as from the holy purpose which it was ordained to serve, that it must have been equally strange, as it was glorious in their sight; for antediluvians occupying possibly on their devoted lands, a portion of its great continent, now covered by the Pacific, might never have witnessed a sun-shine shower. A canopy of clouds indeed might often be stretched in the cooler upper regions of their skies, but the aqueous vesicles in descending through the warmer aerial strata below, would return again to invisible vapour, a process fully described in Book I. chap. 3. In such clouds,

no bow could be set. Heavy dews deposited during the night and early dawn, from the well known influence of a ground chilled by calorific radiation, would supply the place of rain for vegetable sustenance; as now happens in Lima and

regions of our present globe.

many other

I had deduced these corollaries from the hygrometric laws laid down in treating of the atmosphere, before my attention was directed to the following curious historical notice of primeval meteorology. It affords a very beautiful, and to me quite unexpected accordance, between the results of Science and the records of Faith.

"For the Lord God had not caused it to rain' upon the earth, and there was not a man to till the ground. But there went up a mist from the whole earth, and watered the whole face of the ground." Genesis ii. 5, 6.

This document, at which a sciolist might possibly sneer, is in reality a powerful testimony to the truth of Moses.

The rainbow thus becomes a most significant emblem of God's providential regard to man. It is a phenomenon which results from, and declares the remodelled constitution of the terraqueous sphere. It is a type of sin and suffering; of expiation and peace; a vision where the heaven-ward soul may discern the sublimest truths of Revelation and Science. "While the earth remaineth, seed-time and harvest, and cold and heat, and summer and winter, and day and night, shall not cease."

For a long period after the deluge, the earth, at least in its extra-tropical zones, remained relatively

THIS EARTH HAS GROWN DRIER AND WARMER. 603

damp and cold. Abbé Mann infers from an elaborate research, "that the soil and temperature of all the countries from Spain to the Indies, and from Mount Atlas to Lapland and the remotest north, have entirely changed during the course of ages, reckoning from the earliest historical documents to the present time, gradually passing from extreme humidity and cold, to a considerable degree of dryness and warmth; that is to say, from one opposite to another." Abbe Mann's Memoirs, I. 12.

The Hon. Daines Barrington also from a wide induction of historical facts concluded, "that the seasons have become infinitely more mild in the northern latitudes, than they were 16 or 17 centuries ago." Phil. Trans. 1768.

Cæsar says the vine could not be cultivated in Gaul on account of the severity of winter; though that country now affords the highest flavoured wines. The rein-deer was in his time an inhabitant of the Pyrenees; whereas, the Highlands of Scotland are at this day too warm for it. The Tiber was sometimes frozen over, and the ground about Rome covered with snow, for several weeks together. The Romans never experience such intense winter weather in our times.

This progress of heat and desiccation has produced remarkable changes on the land of Egypt. For many generations after the flood, it was a hotbed of vegetation, and swarmed with the animal tribes. Even in the time of Augustus, the granaries of Rome were filled from the corn-fields of Egypt. But the soil of the greater portion of it growing progressively more arid, has now become a mass of incoherent sand, drifted every season closer to the valley of the Nile, by the western winds, circumscribing the fields, and blasting the hopes of the husbandman. No lands capable of tillage now

remain on any portion of the banks of that river, where they are unsheltered by a mountain-ridge.

M. Denon informs us that nothing any longer appears above these sands, but the summits of ruined cities that lie overwhelmed beneath them. "How melancholy to walk over villages swallowed up by the flying dust of the desert, to trample their roofs under our feet, to strike against the very pinnacles of their minarets, and to reflect, that yonder were cultivated fields, that here grew trees, and there stood the dwellings of men, but all have vanished for ever."

Had our continents been as ancient as some have surmised, this scourge of the desert, which has committed such ravages since the days of Cleopatra, should long before that period, have effaced every vestige of human habitation from the western banks of the Nile. The relative condition of such monuments attests the progressive encroachment of the sand; for the fertility and populousness of Egypt have declined visibly with the exhaustion of the diluvian moisture. Had that great cataclysm been more ancient than the epoch assigned by Moses, Egypt ought to have reached its ultimate desolation very long ago. Not an oasis should now remain, no green island in the wilderness, to remind the traveller of those fruitful plains which once extended the whole way to the Nile. Thus the gradual invasion of Egypt by the sands of the desert, becomes a chronometer of our globe.

Berosus, who wrote at Babylon in the time of Alexander, speaks of the deluge nearly in the same terms with Moses, and supposes it to have happened immediately before Belus, the father of Ninus. Though the traditions of some ancient nations who trace back their origin many thousands of ages, seem at first sight to contradict