The men who have thought about and discussed these lights have guessed at three sources, one of which, it seems, ought to be the true one. Some hold that fire circles about the ocean and all the bodies of water that stream about on the outer sides of the globe; and since Greenland lies on the outermost edge of the earth to the north, they think it possible that these lights shine forth from the fires that encircle the outer ocean. Others have suggested that during the hours of night, when the sun’s course is beneath the earth, an occasional gleam of its light may shoot up into the sky; for they insist that Greenland lies so far out on the earth’s edge that the curved surface which shuts out the sunlight must be less prominent there. But there are still others who believe (and it seems to me not unlikely) that the frost and the glaciers have become so powerful there that they are able to radiate forth these flames. I know nothing further that has been conjectured on this subject, only these three theories that I have presented; as to their correctness I do not decide, though the last mentioned looks quite plausible to me. I know of no other facts about Greenland that seem worth discussing or mentioning, only those that we have talked about and what we have noted as the opinions of well-informed men.
XX
THE SUBJECT OF THE NORTHERN LIGHTS CONTINUED
Son. Everything that you have told here seems wonderful to me, though also very instructive, and this fact most of all, that men, as you have pointed out, are able to leave the earth, as it were, and view for themselves the boundaries which God has drawn amid such great perils. Your last remark, however, suggests that there is yet a little matter to inquire about along this same line. In speaking of those three conjectures you said that you think it most likely that these lights have their origin in frost and ice; but just before in describing their appearance, you added that now and then fog and dark mist resembling smoke would mount up among these lights. But even if the cold should be so prevalent there as to give rise to these lights with their fire-like rays, I cannot help wondering whence that smoke can come which sometimes appears to shade and becloud the light till it seems almost quenched; for to me it seems more likely that the smoke is due to heat than to frost. There is one more thing that looks strange to me which you mentioned earlier in your speech, namely that you consider Greenland as having a good climate, even though it is full of ice and glaciers. It is hard for me to understand how such a land can have a good climate.
Father. When you say, in asking about the smoke that sometimes appears to accompany the northern lights, that you think it more likely that the smoke comes from heat than from cold, I agree with you. But you must also know that wherever the earth is thawed under the ice, it always retains some heat down in the depths. In the same way the ocean under the ice retains some warmth in its depths. But if the earth were wholly without warmth or heat, it would be one mass of ice from the surface down to its lowest foundations. Likewise, if the ocean were without any heat, it would be solid ice from the surface to the bottom. Now large rifts may appear in the ice that covers the land as well as openings in the ice upon the sea. But wherever the earth thaws out and lies bare, whether in places where there is no ice or under the yawning rifts in the glacier, and wherever the sea lies bare in the openings that have formed in the ice, there steam is emitted from the lower depths; and it may be that this vapor collects and appears like smoke or dark fog; and that, whenever it looks as if the lights are about to be quenched by smoke or fog, it is this vapor that collects before them.
In reply to your remark about the climate of Greenland, that you think it strange that it is called a good climate, I shall tell you something about the nature of the land. When storms do come, they are more severe than in most other places, both with respect to keen winds and vast masses of ice and snow. But usually these spells of rough weather last only a short while and come at long intervals only. In the meantime the weather is fair, though the cold is intense. For it is in the nature of the glacier to emit a cold and continuous breath which drives the storm clouds away from its face so that the sky above is usually clear.[[231]] But the neighboring lands often have to suffer because of this; for all the regions that lie near get severe weather from this ice, inasmuch as all the storms that the glacier drives away from itself come upon others with keen blasts. Now if this is clear to you, I believe there is no need of giving any further explanation of the subject than what you have now heard.
XXI
THE ZONES OF HEAT AND COLD
Son. These things are all clear to me and it seems reasonable that they should be as you say. Still, there are a few things that you mentioned a little earlier in your talk, which I wish to ask about, if you permit. You said that both sides of the earth are cold, the southern as well as the northern. But I hear it said by all men who come from the regions to the south that the farther south one travels, the hotter the lands are. Likewise all the winds that come from the south are both moister and milder than other winds. In the winter those winds always bring a good thaw, while other winds are so cold that they bring frost, and ice is formed. And during the summer the south wind is still warmer than other winds. Now if my questions do not tire you and I do not seem to ask too much, I should like to have you answer this question too.
Father. When I told you that in the skies three belts are traced under which it is difficult to cross, one torrid and two frigid, I added that the hot belt curves from east to west. But if I have stated this correctly, it will be evident that the cold must be as severe in the southern parts as in the northern.[[232]] I believe, however, that all the regions lying near the hot belt, whether on the south side or on the north, are also hot; but I believe those lands to be frigid which lie very far in either direction. You have stated that all men tell us that the farther south one travels, the greater the heat; but that, I believe, is due to the fact that you have never found any one who has traveled as far south of the hot belt as those lands which we have now talked of lie to the north. You have also said that the winds which come from a southerly direction are warmer than the rest. But it is reasonable that the south wind should be warm when it reaches us, even though it comes from the frozen south side of the earth, for it blows through the curved ring of the torrid belt.[[233]] Consequently, though it blows cold from the south, it is warm when it emerges on the northern side. And if people live as near the cold belt on the southern side as the Greenlanders do on the northern, I firmly believe that the north wind blows as warm to them as the south wind to us. For they must look north to see the midday and the sun’s whole course, just as we, who dwell north of the sun, must look to the south.