which the traveler is advancing, while others gradually disappear in the direction from which he is receding; 5th. That, persons have sailed constantly in one direction, either east or west (as nearly as the different bodies of land on the globe will admit), and returned to the place from which they first set out; 6th. That, in cutting for a canal it is found that allowance must be made for a dip of about eight inches in a mile, in order to keep the water of a uniform depth throughout; 7th. That, the shadow the earth casts upon the moon, during a lunar eclipse, is always circular. How many motions has the earth? Two; a diurnal, or daily motion, on its axis; and an annual, or yearly motion, round the sun. What is the Earth's Axis? It is a straight line which we imagine How long is it in making a complete revolution? Twenty-four hours. What does this revolution cause? The succession of day and night. How long is the earth in making a complete revolution round the sun? A year. What does the earth's revolution round the sun occasion? It occasions, in part, the diversity of the seasons. What is the distance round the earth in a great circle? About twenty-five thousand miles. What is this distance called? The circumference of the earth. What is the distance through the centre of the earth at the equator? Seven thousand nine hundred and twenty-five miles. What is this distance called? The equatorial diameter of the earth. What is the distance through the centre of the earth, from one pole to the other? About seven thousand eight hundred and ninety-nine miles. What is this distance called? The polar diameter of the earth. LESSON II. EXTENT OF THE EARTH'S SURFACE, ETC. How many square miles is the earth's surface supposed to contain? About two hundred millions. What portion of this is land? About one-fourth, or fifty millions. What portion water? About three-fourths, or one hundred and fifty millions. How is the land distributed? There is about three times as much land in the Northern Hemisphere as in the Southern; and two and a half times as much in the Eastern as in the Western Hemisphere. How is the land naturally divided? It is divided into different parts, of various forms, to which geographers have given the names of continent, island, peninsula, isthmus, cape, promontory, mountain, hill, plain, and valley. What are these divisions styled? The natural or physical divisions of the land area of the earth's surface. How is the water naturally divided? The water also is divided into parts, variously formed, which geographers have designated by the names ocean, sea, gulf, bay, strait, passage, sound, channel, lake, and river. What are these divisions called? The natural or physical divisions of the water area of the earth's surface. Why are these divisions styled natural? Because they have not been made by man, but have been formed by nature. What divisions of the earth's surface have been made by man? Empires, kingdoms, states, cities, towns, villages, &c. What are these divisions called? Political divisions. By what means is the earth's surface represented? By means of maps and artificial globes. What are maps? Maps are drawings which represent, on a plane, the whole, or any part, of the earth's surface. What are artificial globes? Artificial globes are balls of wood, or other material, on whose exterior the surface of the earth is delineated or represented. What lines are usually drawn on maps? The equator, meridians, parallels, the tropics, and the polar circles. Do any of these lines actually exist, or, in other words, can any of them be found on the surface of the earth? There are no such lines on the earth. Why then are they drawn upon maps? Because they greatly facilitate our obtaining a knowledge of much that is important for us to know respecting the earth. What do we reckon from the equator? Latitude; and this may be either north or south. What do we reckon from meridians?. Longitude; and this may be either east or west. Of what use are the tropics and polar circles? They serve to designate the respective limits of the several zones of the earth. LESSON III. ZONES, ETC. How many zones are there? Five two frigid zones, two temperate, and one torrid zone. How many distinct kinds of climate do these five zones represent? Three: the coldest, the hottest, and the medium climate. What does the term climate signify? It signifies the prevailing character of the weather at any place. Where, generally speaking, are the hottest countries situated? In the torrid zone. Where are the coldest countries situated? In the frigid zones. Where are the countries situated that generally possess a medium climate? Do the heat and cold of a country depend solely on its situation in one or other of these zones? No; there are various other causes that affect the climate of a country, and regulate its degree of heat or cold. What are the chief causes that affect or determine the climate of any place? The chief causes are:-1st, the latitude of the place; 2d, the height of the place above the level of the sea; 3d, the position and direction of the mountain chains; 4th, its proximity to, or remoteness from, the sea; 5th, the slope of the country, or the aspect it presents to the sun's course; 6th, the geological character of the soil; 7th, the degree of cultivation which it has received, and the density of the population collected upon it; 8th, the prevalent winds; 9th, the annual quantity of rain that falls. These causes, acting together, or separately, determine the character of the climate of a country. What is the breadth of the torrid zone? The breadth of the torrid zone is forty-seven degrees. What is the breadth of the temperate zones ?. Forty-three degrees each. What is the breadth of the frigid zones? Twenty-three and one-half degrees each. Into how many branches is the science of Geography divided? It is divided into three branches; viz., Natural, or Physical, Political, and Mathematical, or Astronomical. What is Physical Geography? Physical Geography is that branch of science which includes a description of the solid and fluid parts of the earth's surface; of the atmosphere which surrounds it, and of all animal and vegetable life. What is Political Geography? Political Geography is that branch of science which includes a description of the various countries on the earth's surface, their government, people, language, religion, and customs. What is Mathematical Geography? Mathematical Geography is that branch of science which includes a description of the earth as a planet, treating of its form, its magnitude, its motion, and of the various imaginary lines upon its surface. |