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share of the breezes which come from the warm south. Winds take up a portion of the heat, or cold, or moisture over which they have passed ; and the greater the extent they have passed over, the more hot, or cold, or moist they are. Thus the cold winds in this country are those which blow from the north pole. They are cold enough at times, I am sure; but as Persia is more distant than England from the polar region, I should expect to find the wind that blows from thence and passes over the vast frozen plains of Russia in winter, to be much colder than we find such winds here. I should not wonder to be told something of this sort happens near the Caspian Sea.
H. Why there particularly, Sir ?
Mr. D. Because thereabout the wind might have a full sweep from the polar regions, whereas more to the west it would be somewhat intercepted by the mountains between the Black and the Caspian Seas. · U.0. There you are perfectly in the right, Sir, as I shall have to show directly.
H. I suppose, Sir, it must be terribly hot in those regions near the middle of the earth, where there are no mountains ?
Mr. D. We may safely say that the heat would be intolerable between the tropics at that time of the year when the sun is immediately overhead, if there were nothing to soften the natural heat of that season; but just at that time the rainy weather commences, and greatly mitigates the intensity of the heat. When the sun returns to the other half of the torrid zone, so that his beams do not come straight down, the heat is not naturally so great, and then the climate is frequently delightful, even between the tropics. From causes of this class, for example, Lima and Quito in Peru, which lie within the tropics, have as fine a climate, perhaps, as any upon earth.
H. Then I suppose that, as there is no coun-. try that is uninhabitable on account of the heat · Mr. D. Nay, Henry, I did not say that. I dare say there are, both within and without the torrid zone, many sandy deserts perfectly uninhabitable, though not merely on account of their latitude. But go on. · H. I was going to say, I supposed that, in the same manner, there was none too cold for men to live there.
· Mr. D. Here (pointing to the poles of the artificial globe), in the regions near the poles, it is impossible for men to inhabit, although tradition states that men could formerly live nearer the north pole than now. In these regions the climate seems more uniform than anywhere else on the globe : always intensely cold-colder even in summer than we ever feel it in winter. Commonly we may say that the summers of very cold countries are exceedingly warm in consequence of he great length of their days. Thus, as we proceed from the tropics towards the poles the summers increase generally in warmth, and the winters in coldness. In Greenland, where the winters are so long and so dreadfully cold, the summer heat is so great as to melt the pitch on the vessels; and at Tornea in Lapland, notwithstanding the slanting direction in which the beams of the sun come there the heat during the summer is nearly as great as that of the torrid zone, because the sun is there almost always above the horizon. The difference between winter and summer is least within the torrid zone, and within the polar circle. I was just telling you that the length of the days generally renders the summers warm; yet in the regions near the poles, where the sun
is longest above the horizon, the ice never thaws. The beams of the sun come so much aslant and are so feeble, as to produce no sensible effect on the immense masses of ice which seem to increase in magnitude every year. It has been calculated that a space of nearly a million of square miles around the north pole, and a million and half or more around the south pole is thus covered at all seasons with masses of impenetrable ice.
Now, my dear boys, I hope this account of the causes which influence climate will enable you the better to understand Mr. Oldcastle's account of the climate of Persia, and the other countries he is going to describe.
U. O. We are very much obliged to you for your explanation, Mr. Dillon; and my accounts of climate will frequently confirm and illustrate the general statement you have made, which I hope we shall all keep well in mind. Now, let us return to Persia, from which we have wandered to the torrid zone and to the polar circles.
You will now clearly understand, that in a country the surface of which is very unequal, like that of Persia, there must needs be great inequality of climate. If we could suppose the mountains all shorn away, the surface of the country generally would remain a high tableland, varying from 2500 to 3500 feet above the level of the sea. Upon this the mountains are piled to the height, in some places, of 7000 or 8000 feet. What effect do you imagine this elevation must have on the climate of the country?
H. I suppose it makes it colder than it would be else.
U. O. Yes; it seems as if there were a struggle between the elevation to make Persia a cold country, and the latitude to make it a hot one. The result is, that, in general, the climate is in the winter very cold, and very hot in the summer; yet then the nights are commonly cold enough to afford a strong and sometimes distressing contrast to the heat of the day. When the Persian Ambassador was in this country, he was much troubled at first because the people at the inns supposed Persia a very hot country, and almost smothered him with bedclothes, that he might not suffer from the difference between this country and his own. This was very kind; but the truth was that his Excellency was much better able to bear cold,