We owe much to dogs in arctic explorations. It would have been impossible to penetrate to the interior of arctic lands or to traverse the frozen seas but for the services of the faithful dogs trained to draw sledges. Many of these animals have suffered from overwork and have perished from starvation; others have been sacrificed for food in dire extremities to preserve the lives of their masters. Surely arctic service has proved as destructive to the poor dogs as to men. FOOTNOTES: [Footnote 1: Isolated masses of native iron are usually of meteoric origin, but to determine whether or not the native iron fell from the sky a portion of the surface is ground off and polished; then the polished surface is etched with acid. If crystalline lines are plainly brought out, there can be no doubt of its being of meteoric origin. The following excerpt from the American Museum Meteoric Guide will make the matter clear: "The iron of meteorites is always alloyed with from six to twenty per cent of nickel. This 'nickel-iron,' as it is commonly called, is usually crystalline in texture, and when it is cut, polished, and 'etched' a beautiful net-work of lines is brought out, indicating plates which lie in positions determined by the crystalline character of the mass. This net-work of lines constitutes what are called the Widmannstattian figures, from the name of their discoverer. When these figures are strongly developed the meteoric origin of the iron cannot be questioned, but their absence does not necessarily disprove such an origin. Native iron of terrestrial origin is extremely rare."] CHAPTER XII POLAR REGIONS--ANTARCTICA A continent twice the size of the United States lies sleeping beneath a mantle of snow and ice at the south pole. No vegetation save a few mosses and lichens exists anywhere on this vast expanse. No four-footed animals rove over it; no human beings inhabit it. Hundreds of thousands of square miles of pack-ice, glaciers, and ice-walls jealously guard it on all sides. On one side, for a distance of five hundred miles, extends a great ice barrier whose perpendicular ice-wall is from thirty to three hundred feet in height. Behind this wall are vast ice-fields, and beyond these immense plateaus of ice having an elevation of six thousand to twelve thousand feet where fierce winds and a biting cold prevail. On these elevated plains the thermometer stands in the middle of summer sometimes as low as forty degrees below zero. Great fields of ice and huge icebergs cover the sea in all directions and in winter extend far beyond the antarctic circle. In these regions the ice forming on the surface of the ocean attains a thickness varying from five to seventeen feet. Long ranges of snow-clad and ice-mailed mountains are found with ermined peaks towering from ten thousand to fifteen thousand feet in height.