tude, the winters are milder in Patagonia and Tasmania than they are in the corresponding latitudes in Russia and Italy.

No inhabited land has been discovered in the southern hemisphere beyond 54° or 55° of latitude; while in the northern hemisphere, habitations of men are found beyond the 70th parallel. Snow has been seen to fall at the Straits of Magellan in the middle of summer; and the island of South Georgia, which is about the same distance from the equator to the south, as Yorkshire in England is to the north, is covered with perpetual snow. Its only plants are lichens and mosses. Compare also, the climate of the Isle of Man.

Three causes have been assigned for the difference in temperature between the northern and southern hemispheres. First, the great difference in the distribution of land and water in the two hemispheres (see p. 72). Secondly, as the sun is nearly eight days in the year longer on the northern side of the equator, than he is on the southern, a greater quantity of heat is distributed in the northern hemisphere than in the southern. And thirdly, as almost all the ice that is formed about the south pole escapes, and is carried by the currents towards the equator,d the cold which it gives out as it gradually approaches warmer latitudes, cools the atmosphere and lessens the temperature in proportion. The ice from the north pole, of course, has a similar effect upon the northern hemisphere, but much of the ice that is formed there is hemmed in by the land, and prevented from escaping.

The island of South Georgia is in 54o 5′ S. lat.; and 38° 15′ W. lon. That portion of the earth's orbit which lies above the sun, or north of the equator, contains about 184°; that under the sun, or south of the equator, about 176°; and hence the sun, in the course of the year, is nearly eight days longer in the northern than in the southern hemisphere. Or, in other words, the time between the vernal and autumnal equinoxes is about seven days seventeen hours longer than the period between the latter and the former. This arises from the elliptical form of the earth's orbit and from the earth's being in aphelion in summer.

Sir John Herschel has shown that owing to the greater proximity of the earth to the sun during the southern summer, both hemispheres receive an equal amount of heat.

d In 1854, an iceberg was met with in the Southern Ocean which was estimated to be 50 miles long, 4 miles broad, and 150 feet high.

QUESTIONS FOR EXAMINATION ON CHAP. VI.

Pages 102-106.—What causes a diversity of temperature? 2. Where and when is it greatest? 3. The meaning of the terms zone and climate? 4. How many zones ? 5. Their names? 6. Why so called? 7. The boundaries of each zone? 8. The extent of each in degrees? 9. Why will not the extent in degrees give their real magnitudes ? 10. Can you give an estimate of their comparative magnitudes? 11. The necessity for a further division of the earth's surface with regard to temperature? 12. What may climates be regarded as? 13. The principle upon which the division into climates is made? 14. In what part of the earth are the days and nights equal throughout the year? 15. How many climates between the equator and each of the polar circles? 16. Why 24? 17. From the polar circles to the poles the climates are reckoned not by half hours but by? 18. Why by months? 19. Why six climates between the polar circles and the poles? 20. Why is the division of the earth into climates not much regarded now? 21. Can you give an example of this? 22. The difference between the temperature of Labrador and Ireland in the same latitude? 23. The inference from this and similar facts? 24. The temperature of a place generally depends upon? 25. How is this general principle modified? 26. What are the cities mentioned as having the same mean temperature though at very different distances from the equator? 27. How do you explain this? 28. Why the northern parts of North America and Asia colder than places in the same latitude in Europe? 29. Why does a declivity towards the equator increase the temperature? 30. Can you state the facts and illustrations given in the notes ? 31. Why the north of Africa and south of Europe warmer than the same latitudes in America and Asia? 32. How do periodical and prevailing winds affect climate? 33. How large tracts of water? 34. What effect has an insular situation upon climate? 35. Give examples.

Pages 106-109.-What is meant by isothermal lines? 2. The necessity for them. 3. How is their direction generally determined: 4. In what part of the earth do they, generally speaking, coincide with the parallels of latitude? 5. Why is their course irregular in higher latitudes? 6. Why will an isothermal line of any given temperature recede farther from the equator in Europe than it will either in America or Asia? 7. And why in the maritize parts of Europe than in the continental or elevated regions? 8. The mean temperature of the earth at the equator? 9. And at 20° north or south of it? 10. Can you state the most important isothermal lines? 11. Can you describe the seven vegetable zones into which the isothermal lines specified divide the earth's surface? 12. Is it meant that the plants and vegetables here specified are confined to those particular regions? 13. Can you give a description of the several vegetable zones which you might expect to meet with in ascending a lofty mountain in the torrid zone! 14. What is said of Teneriffe, Mount Ararat, and Etna?

Pages 109-111.-What is meant by Isotheral and Isochimenal lines? 2. The necessity for them? 3. Give examples. 4. The difference between the mean summer and mean winter temperatures of places increases as? 5. Give examples from the annexed table.

Pages 111-114.-What is meant by the snow-line? 2. Generally speaking, where is it highest? 3. Where does it touch the surface? 4. Its height at the equator? 5. At 20 degrees from the equator? 6. Its height in our latitude? 7. Is the height of the snow-line in different latitudes accurately ascertained? 8. How might a person at the equator experience the cold of the frigid zones? 9. Can you explain why the snow-line is higher at 20° from the equator than it is at it? 10. Can you explain why the temperature decreases in proportion to the elevation? 11. Why do we feel warmer walking along the paved streets of a town than we should if walking through a field in the country? 12. Why should we expect the snow-line to be lower in the southern than in the northern hemisphere in equal latitudes? 13. What has Humboldt said respecting the temperatures of the two hemispheres? 14. Can you give examples of the difference of temperatures in the same latitudes? 15. How do you show by the habitations of men that the southern hemisphere is colder than the northern? 16. Can you state the three causes assigned for the difference in the temperatures of the northern and southern hemispheres? 17. Why is the sun nearly eight days in the year longer on the northern side of the equator than he is on the southern?

CHAPTER VII.

MOUNTAINS AND TABLE LANDS.

At first view, MOUNTAINS appear to be irregularities on the earth's surface; but a little consideration will convince us that they were destined to perform an important part in the economy of nature. Their beneficial effects upon climate and vegetation, in countries exposed to a vertical sun, we have already spoken of; and we have now to add, that mountains form an essential part of the aqueous machinery of nature, by which the earth is refreshed and fertilized. Mountains intercept the clouds in their passage through the air, and by attracting, condense and cause them to fall, in rain, hail, or snow, according to the temperature and state of the atmosphere. All the moisture produced in this way penetrates through the pores and fissures of the mountains, and is collected in subterranean cavities and internal reservoirs; and hence the origin of springs, brooks, and rivers, For when these subterranean reservoirs overflow, the water issues out in springs, which, following the declivity of the ground, unite their streams with others, and thus gradually swell into brooks and rivers. If there were no such elevations on the earth's surface, the moisture deposited upon it by the process of evaporation and condensation would in

dry and sandy soils be entirely absorbed; while in others, it would saturate the surface, and produce swamps and

morasses.

Again, without mountains, the mineral treasures of the earth would have been beyond the reach of man.

"If," as has been said, "the strata of the earth had enveloped it like a shell, or to use a familiar example, had they surrounded it like the coats of an onion, it is clear that we should never have become acquainted with any other than the upper members of the series; and that the beds of coal and salt, and the ores of the metals, all of which are confined to the inferior strata, could never have been made available for the purposes of man."

Now, the mountains, those great eruptions of nature, have, by breaking up the crust of the earth, and by displacing the upper strata, brought within the reach of man those mineral treasures to which otherwise he never could have penetrated.

The novelty and beauty given to the landscape, by the varying form and diversified scenery of hill and dale, and mountain and valley, are too obvious to dwell upon. How different would the face of nature be, if the surface of the earth were one unbroken and monotonous plain !

We shall conclude our observations upon mountains, by directing attention to the following excellent article on this subject from a popular publication:"

"The hills are the bones of a country, and determine its form just as the bones of an animal do. For according to the direction of the hills, must be the course of the rivers. If the hills come near the sea, it makes the rivers very short, and their course very rapid; if they are a long way from the sea, it makes the rivers long and gentle. But rivers of the latter sort are generally navigable, and become so large near the sea as to be capable of receiving ships of large size. Here then towns will be built, and these towns will become rich and populous, and so will acquire popular importance. Again, on the nature of the hills depend the mineral riches of a country; if they are composed of granite or slate, they may contain gold, sil ver, tin, and copper; if they are composed of the limestone of Derbyshire or Durham, they are very likely to have lead mines; if of the sand or gritstone of Northumberland, Lancashire, and Yorkshire, it is probable that there will be coal at no great distance. On the contrary, if they are made up of the yellow limestone of Gloucestershire, Oxfordshire, and Northamptonshire; or of chalk, like the hills

The Penny Magazine.

in Wiltshire, Berkshire, and Hampshire; or of clay, like those about London; it is quite certain that they will contain neither coal nor lead, nor any valuable mineral whatsoever. But on the mineral wealth of a country, and particularly on its having coal or not having it, depends the nature of the employment of its inhabitants. Manufactories are sure to follow coal; whereas in all those districts of England where there is no coal, that is in all the counties to the south-east of a line drawn from the Wash in Lincolnshire to Plymouth, there are generally speaking, no manufactories, but the great bulk of the people are employed in agriculture.

"Thus, then, on the direction and composition of the hills of a country, depend, first of all, the size and character of its rivers. On the character of its rivers depend the situation and importance of its towns, and its greater or less facilities for internal communication and foreign trade. And again, on the composition of the hills, depend the employment of the people, their number on a given space, and in a great degree their state of morals, intelligence, and political independer.ce."

To facilitate the study of this important branch of Geography, we have arranged and CLASSED the principal mountains of the globe in the order of their height, according to the best and most recent authorities; and with this view we have also given a brief sketch of the principal mountains in the four great divisions of the world.

MOUNTAINS IN THE ORDER OF THEIR HEIGHT.a
Ten Classes.

FIRST CLASS.-Mountains 20,000 feet above the level of the sea, and less than 30,000. This class comprises a large number of the Himalayan Mountains, and a few of the Andes. The highest of the Himalayan Mountains are Mount Everest (lat. 28° N., long. 86° E.), 29,002 feet; Kunchin-junga, 28,177; Dhawalagira, or the White Mountain, 26,460; Juwahir, 25,670; Jumnautri, 25,500; Chumalari, 23,946. And the more elevated of the Andes are Aconcagua, 23,910 feet; Sahama, 22,350; Chimborazo,*b 21,464; Sorata, 21,286; and Illimani, 21,145. In eastern Africa, Kenia, 22,814; and Kilimandjaro, 20,000.

a By the height of mountains is usually meant their perpendicular elevation above the sea level. With regard to the elevation of several of the following mountains, the authorities differ. This is not surprising, as, with few exceptions, it is only in Europe that accurate measurements have been taken. And with regard to the highest mountains, it would be impossible to determine how much of their elevation is due to the condensed masses of snow which have accumulated on their summits since the world began.

b The mountains thus marked (*) are volcanoes.