which the cold air leaves empty when it shrinks. For air, like water, is always ready to flow in wherever it finds a vacant space. 4. And so, if the earth stood still, there would be a wind always rushing towards the north pole, and another wind always making towards the south pole. But there must be more than that. If only that went on, all the air would soon get to the poles; there would be too much air at the poles, and too little at the tropics. Therefore the air from the poles rushes back to the tropics, to fill up the space left empty there. 5. You have seen the same thing happen a thousand times. Why does the cold air, if there be a fire in the room, stream in through an open window or through a crack, and so make a draught? Because the fire heats the air in the room; and it becomes light, and flies away up the chimney, as the light hot air does towards the poles. But that leaves too little air in the room; and so the cold air rushes in through the key-hole, and under the doors, just as the cold air rushes from the poles to the tropics. 6. The mere difference of heat between the tropics and the poles would make two winds, even if the earth stood still. But the earth does not stand still. It turns round on its axis once every twenty-four hours; and thus the course of the winds is altered, and, instead of blowing due north and south, they blow generally north-east and south-west. 7. You all know that when you are traveling in a carriage your body is moving on with the same speed as the carriage, and keeps that speed if you jump out, till you touch the ground, and are stopped suddenly by it so that, if you jump out forward, the speed which your body has caught from the carriage will throw you on your face if you do not take do not take care; while if you jump out backward the same speed will throw you on your back, and has stunned many a foolish person ere now by a tremendous blow on the back of his head. 8. Now, let us apply that same law to the air at the tropics. The earth there is 24,900 miles round, and it turns round once every twenty-four hours, from west to east. Now divide 24,900 by 24. What have you? 1,037 miles. Therefore every little atom of air at the tropics is going eastward with the earth at the rate of more than a thousand miles an hour. But as the air travels north the earth's circumference grows smaller. 9. This you may prove for yourselves by measuring on the globe. But as it all turns round in the same time, twenty-four hours, each spot on the globe is turning more slowly, the farther north it is. Look, for instance, at St. Petersburg in Russia. There it is only about half as far around the earth from east to west as it is in the tropics: so that St. Petersburg is moving eastward only half as fast as a point on the equator moves. 10. But the hot air from the equator keeps up to something of that tremendous pace of a thousand miles an hour eastward with which it started; and when it comes up to us here, it is going eastward much faster than we are, and when it gets as far north as St. Petersburg, much faster still. It is traveling east as well as north: therefore it is traveling, on the whole, north-east. 11. But we name the winds, not by the quarter which they are going to, but by the quarter which they are coming from; and, as this wind comes to us from south and from west, we call it a south-west wind. 12. Why does not the south-west wind strike us here at the pace of hundreds of miles an hour? It blows usually some ten to twenty miles an hour only, and if it blows as hard as sixty miles an hour we call it a terrible storm. How is there not a perpetual hurricane here, such as sometimes comes in the tropics, such as no man nor house could stand upright in? fiercest 13. I will tell you. The air is stopped by friction against other air, and against the earth. The southwest wind comes up to us here — even the very gale-like a spent bullet bearing its course through the air. It has to fight its way up against the earth, with its hills and trees and houses all trying to stop it, and against the north-east winds too, which are rushing in the opposite direction; and it is continually checked and baffled by them; and the fiercest gale we ever felt is but a little strip or flake of it, which has, as it were, escaped, and run away for a few hundred miles. 14. And now let us talk a little of that north-east wind, and why it does not come straight from the north all the year round. Because, as with the south-west wind, the earth moves eastward on its axis. Now, the north pole simply stands still, and turns round on itself, like the axle of a wheel, in the midst of snow and ice. But, since the pole is not moving eastward, the air round it is not moving eastward either; and therefore the cold air which starts from the pole to go south starts without any inclination to go east. 15. But as it moves south, it finds the earth under it flying round eastward faster and faster. The earth is meeting it continually from the westward, and this is why we often feel the north wind as a north-east wind: we are rushing against it as we go east. So we have a north-east wind going from the north pole to the tropics, and a south-west wind going from the tropics to the pole. HEADS FOR COMPOSITION. I. AIR AS AFFECTED BY HEAT: why hot air is lighter than cold- the result of this air in the tropical regions—in the polar regions. II. WHAT MUST HAPPEN THEN: interchange of air between Torrid and Frigid zones — effect on the winds if the earth stood still-effect of the earth's daily rotation in changing the course of the winds. III. EFFECTS IN DETAIL: explanation of the north-east winds - of the south-west winds. 65.-The Bells of Shandon. çğm’balş, musical instruments. ki-Ŏsk', Turkish summer-house. min'a-rets, slender, lofty turrets. spells, charm, enchantment. PREPARATORY NOTES. These beautifully musical verses are by Francis Mahony (1804–1866), a native of Cork, Ireland, and widely known as a contributor to various English periodicals, under the pen-name of "Father Prout." (1) Shandon bells: i.e., the bells of St. Anne Shandon's church, a chime celebrated for its sweet harmony. (2) Lee: the city of Cork is situated on the river Lee. - (5) Adrian's Mole: i.e., the castle of St. Angelo, with massive tower, called from its founder, the emperor Hadrian, the "Mole of Hadrian."— (5) Vatican: the great palace of the Roman pontiff. (5) Notre Dame: the cathedral of that name at Paris.(7) St. Sophia: a gorgeous mosque at Constantinople. With deep affection and recollection, I often think of those Shandon bells Whose sounds so wild would, in days of childhood, Fling round my cradle their magic spells. On this I ponder where'er I wander, And thus grow fonder, sweet Cork, of thee,With thy bells of Shandon, that sound so grand on The pleasant waters of the river Lee. I've heard bells chiming full many a clime in, While at glib rate brass tongues would vibrate: |