Excerpt from Philips' Atlas of Physical Geography for the Use of Schools: Illustrating the Natural Features of the Globe, the Geographical Distribution of Natural Phenomena, and Their Connexion With the Industrial Pursuits of Mankind The two principal Lines of No Variation shown on the chart are obviously but the opposite sides of one great circular line passing round the globe, and forming a Magnetic Meridian. There are two places on this line - one in the northern and the other in the southern hemisphere - towards which the extremities of the needle, in whatever part of the globe, are always directed. These are known as the Magnetic Poles. The place of the North Magnetic Pole (in about lat. And nearly under the meridian of 94° W., that is, adjoining the Arctic shores of America) is shown on our map. The South Magnetic Pole, the place of which does not fall within its limits, is in a nearly correspondent latitude of the southern hemisphere, under the meridian of 150° east (nearly due south from Tasmania.) The needle always points to these poles; hence the amount of deflection from the true meridian (which is a line joining the opposite extremities of the earth's axis) continually increases with every successive degree of departure from the place of the magnetic meridian, or line of no variation. Upon one side of either of the lines shown on the chart the deflection of the needle is to the westward, and upon the other side to the eastward, of the true north. In passing round the place of either magnetic pole, the needle would make a complete circle (its north or south point, as the case might be, remaining constantly directed towards its own pole), so that the direction of its extremities, with reference to the true north and south, would become actually reversed. That is (taking the northern magnetic pole as an example), the amount of deflection, or variation, would keep on increasing until it arrived at and when at that precise amount the North end of the needle would point due south, and the reverse. The Lines of N 0 Variation are not fixed They oscillate to and fro over the earth's surface, and, with their movement, the amount of deflection or variation at any given place undergoes continual change. In 1660, one of the lines of No Variation passed through London, the needle in that year pointing, at London, due north. It then commenced a deflection to the west of north, the amount of this deflection increasing until it attained, in 1818, a maximum of Since that time, it has been slowly returning to the east ward. In 1858, (the date represented by the chart), the variation at London was nearly 22° west. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Excerpt from Philips' Atlas of Physical Geography for the Use of Schools: Illustrating the Natural Features of the Globe, the Geographical Distribution of Natural Phenomena, and Their Connexion With the Industrial Pursuits of Mankind This Map is designed to illustrate the prime elementary truths of Physical Geography, displaying them in a form which is obvious to the eye, as well as capable of ready appreciation by the reflective faculties of the learner. Physical Geography is the geography of the natural world. The first essential in a study of the truths which it embodies is an adequate conception of the way in which Land and Water are distributed over the surface of the globe. The Land may be regarded under three aspects - 1st, Position and comparative extent; 2d, Contour or shape; 3d, Superficial aspect, or form of relief. The first and second of these points of view are illustrated in the delineations afforded by the Map itself; in the case of the third, the appended Table (of high-land and low-land regions) serves as a supplement to the Map, and supplies such deficiencies as are inherent to it. The Map of the World delineated on the plane of a meridian 20 ̊ west of Greenwich exhibits an Eastern and a Western Hemisphere, and shows admirably the respective grouping of the land-masses that constitute the Old and the New Worlds. The Old World is of the larger extent, and the more solid in shape. But this single illustration is not sufficient. The land and water must be viewed also under the conditions of a Northern and a Southern Hemisphere, as in the case of the smaller appended map, in the lower left-hand corner of the plate. Further, the world must be regarded under the conditions of a division which brings the greatest possible amount of Land-surface within the limits of one hemisphere, and the greatest amount of Water-surface into the other half. This is accomplished by a line of division 90 ̊ distant on every side from London - or, in other words, by a projection made on the plane of the horizon of London, and coincident with what would be obtained on the artificial globe by elevating the north pole 511⁄2 ̊ (the latitude of London) above the horizon. The facts which this plate serves to illustrate, and the conclusions to which it points, are summed up in the second chapter of "the Class-Book of Physical Geography." Physical Map Of The World, Showing The Chief Natural Divisions Of The Land, And The Ocean Currents. This plate carries the learner forward, in his study of the natural aspects of the globe, by a highly important stage. From the first conception of the general forms of Land and Water, he proceeds to examine more closely the aspects and properties of each. The Land exhibits not merely its high-land masses and its expanse of plain, but has besides its mountain-chains, its steppes, prairies, savannahs, pampas, and deserts. The Water has its currents, or ocean-streams. All of these are delineated on the present Map. It is of the highest importance in physical geography to study thoroughly the direction of mountain-chains. These give their form and slope to the lower grounds, and determine the courses of the rivers. The strong black lines (which mark, in the present Map, the mountain-chains) show at a glance the predominant direction of east and west in the high-lands of the Old World, and, in a manner more strongly marked, that of north and south in the case of the New World. But there are exceptions to the rule, in the instance of each. The transverse chains determine, in many cases, the lateral limits of the great river-basins, as the greater chains do their slope and general area. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com