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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 ex
. 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? See Plate XI. Fig. 1.
26. And would not the aurore become more frequent after the approach of winter; not only because more visible in 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 who live in the rarer air of more southern latitudes? And would it not, in that case, although in itself a com
plete and full circle, extending perhaps ten degrees from the pole, appear to spectators so placed (who could see only a part of it) in the form of a segment, its chord resting on the horizon, and its arch elevated more or less above it, as seen from latitudes more or less distant, darkish in color, but yet sufficiently transparent to permit some stars to be seen through it?
28. The rays of electric matter issuing out of a body, diverge by mutually repelling each other, unless there be some conducting body near to receive them; and if that conducting body be at a greater distance, they will first diverge, and then converge in order to enter it. May not this account for some of the varieties of figure seen at times in the motions of the luminous matter of the aurora; since it is possible, that, in passing over the atmosphere from the north, in all directions or meridians, towards the equator, the rays of that matter may find, in many places portions of cloudy region, or moist atmosphere under them, which (being in the natural or negative state) may be fit to receive them, and towards which they may therefore converge; and when one of those receiving bodies is more than saturated, they may again diverge from it, towards other surrounding masses of such humid atmosphere, and thus form the crowns, as they are called, and other figures, mentioned in the histories of this meteor?
29. If it be true, that the clouds which go to the polar regions carry thither the vapors of the equatorial and temperate regions, which vapors are condensed by the extreme cold of the polar regions, and fall in snow or hail; the winds which come from those regions ought to be generally dry, unless they gain some humidity by sweeping the ocean in their way; and, if I mistake not, the winds between the northwest and northeast