the society of men, but was visited nightly by genii and spirits of the first rank, who loved him, and amused him with their instructive conversation. Belubel, the strong, came one evening to see Albumazar. His height was seven leagues, and his wings when spread might overshadow a kingdom. He laid himself gently down between the long ridges of Elluem; the tops of the trees in the valley were his couch; his head rested on Calabut as on a pillow, and his face shone on the tent of Albumazar. The magician spoke to him with rapturous piety of the wisdom and goodness of the Most High, but expressed his wonder at the existence of evil in the world, which he said he could not account for by all the efforts of his reason. "Value not thyself, my friend," said Belubel, “on that quality which thou callest reason. If thou knewest its origin and its weakness, it would rather be matter of humiliation." "Tell me then," said Albumazar, "what I do not know; inform my ignorance, and enlighten my understanding." "Contemplate," said Belubel, "the scale of beings from an elephant down to an oyster. Thou seest a gradual diminution of faculties and powers, so small in each step that the difference is scarce perceptible. There is no gap, but the gradation is complete. Men in general do not know, but thou knowest, that in ascending from an elephant to the infinitely Great, Good, and Wise, there is also a long gradation of beings, who possess powers and faculties of which thou canst yet have no conception." DCCXXXIII AURORA BOREALIS I 1. Air heated by any means becomes rarefied and specifically lighter than other air in the same situation not heated. 2. Air being thus made lighter rises, and the neighboring cooler, heavier air takes its place. 3. If in the middle of a room you heat the air by a stove, or pot of burning coals near the floor, the heated air will rise to the ceiling, spread there over the cooler air till it comes to the cold walls; there being condensed and made heavier, it descends to supply the place of that cool air which had moved towards the stove or fire, in order to supply the place of the heated air which had ascended from the space around the stove or fire. 4. Thus there will be a continual circulation of air in the room, which may be rendered visible by making a little smoke; for that smoke will rise and circulate with the air. 5. A similar operation is performed by nature on the air of the globe. Our atmosphere is of a certain height, perhaps at a medium miles. Above that The height it is so rare as to be almost a vacuum. air heated between the tropics is continually rising, and its place is supplied by northerly and southerly winds which come from those cool regions. I First published in Mr. Vaughan's edition of the author's writings. Mr. Vaughan says: “If I mistake not, the paper was read at the Royal Academy of Sciences at Paris, at the meeting held immediately after Easter, 1779."-EDITOR. 6. The light, heated air, floating above the cooler and denser, must spread northward and southward, and descend near the two poles, to supply the place of the cooler air which had moved towards the equator. 7. Thus a circulation of air is kept up in our atmosphere as in the room above mentioned. 8. That heavier and lighter air may move in currents of different and even opposite directions, appears sometimes by the clouds that happen to be in these currents, as plainly as by the smoke in the experiment above mentioned. Also in opening a door between two chambers, one of which has been warmed, by holding a candle near the top, near the bottom, and near the middle, you will find a strong current of warm air passing out of the warmed room above, and another of cool air entering it below, while in the middle there is little or no motion. 9. The great quantity of vapor rising between the tropics forms clouds, which contain much electricity. Some of them fall in rain, before they come to the polar regions. 10. If the rain be received in an isolated vessel, the vessel will be electrified; for every drop brings down some electricity with it. II. The same is done by snow and hail. 12. The electricity so descending in temperate climates is received and imbibed by the earth. 13. If the clouds are not sufficiently discharged by this means, they sometimes discharge themselves suddenly by striking into the earth, where the earth is fit to receive their electricity. 14. The earth in temperate and warm climates is generally fit to receive it, being a good conductor. 15. A certain quantity of heat will make some bodies good conductors that will not otherwise conduct. 16. Thus wax rendered fluid, and glass softened by heat, will both of them conduct. 17. And water, though naturally a good conductor, will not conduct well when frozen into ice by a common degree of cold; not at all where the cold is extreme. 18. Snow falling upon frozen ground has been found to retain its electricity; and to communicate it to an isolated body, when after falling it has been driven about by the wind. 19. The humidity, contained in all the equatorial clouds that reach the polar regions must there be condensed and fall in snow. 20. The great cake of ice that eternally covers those regions may be too hard frozen to permit the electricity, descending with that snow, to enter the earth. 21. It will therefore be accumulated upon that ice. 22. The atmosphere, being heavier in the polar regions than in the equatorial, will there be lower; as well from that cause as from the smaller effect of the centrifugal force; consequently the distance to the vacuum above the atmosphere will be less at the poles than elsewhere; and probably much less than the distance (upon the surface of the globe) extending from the pole to those latitudes in which the earth is so thawed as to receive and imbibe electricity; the frost continuing to latitude 80, which is 10 degrees or 600 miles from the pole, while the height of the atmosphere there, of such density as to obstruct the motion of the electric fluid, can scarce be estimated above miles. 23. The vacuum above is a good conductor. 24. May not, then, the great quantity of electricity brought into the polar regions by the clouds, which are condensed there, and fall in snow, which electricity would enter the earth, but cannot penetrate the ice; may it not, I say (as a bottle overcharged) break through that low atmosphere and run along in the vacuum over the air towards the equator, diverging as the degrees of longitude enlarge, strongly visible where densest, and becoming less visible as it more diverges; till it finds a passage to the earth in more temperate climates, or is mingled with their upper air? 25. If such an operation of nature were really performed, would it not give all the appearances of an AURORA BOREALIS? 26. And would not the aurore become more frequent after the approach of winter; not only because more visible in the longer nights, but also because in summer the long presence of the sun may soften the surface of the great ice cake, and render it a conductor, by which the accumulation of electricity in the polar regions will be prevented? 27. The atmosphere of the polar regions being made more dense by the extreme cold, and all the moisture in that air being frozen, may not any great light arising therein, and passing through it, render its density in some degree visible during the night-time, to those |