It is desirable thus to have before us a general sketch of the Arctic economy before proceeding to the contemplation of the achievements of discoverers. We shall better appreciate their labours, their splendid efforts extending over centuries, if we know what they did not know, the results of their combined victories over the mighty obstacles which Nature placed in their way. CHAPTER II ICE AND ICEBERGS A knowledge of the nomenclature of polar phenomena is an essential preliminary to the study of the history of Arctic adventure. We must know the meanings of words which constantly recur and which form, as it were, the dialect of our subject. We begin then with the names for different forms and appearances of polar ice. It used to be thought that ice could only be formed in creeks and inlets of the coast. It is now known that young ice forms on the surface of the open sea, and thickens into dense masses, where it is not disturbed by waves. _Young ice_ then is the thin film first formed on the surface of the sea, when the temperature is sufficiently low in the autumn. When it becomes rather thicker it is called _bay ice_. In a ruffled sea the pieces of _bay ice_ strike each other on every side, becoming rounded and having the edges turned up. This is _pancake ice_. In a year, under favouring circumstances, the ice attains a thickness of six feet, in two years of nine feet. Sometimes masses of ice under-run each other, and the result is a thickness of 20 to 50 and even 100 feet. A _field_ is an expanse of ice of such extent that its termination is not bounded by the horizon. A _floe_ is the same as a _field_ except that its whole extent can be seen. _Floe bergs_, occurring on the northern shores of the polar ocean, are large masses of sea ice, broken off from ancient floes of great thickness, and forced upon the shore. _Ground ice_ is formed on rivers or shallow inlets while the sea, as a whole, remains unfrozen. _Land ice_ or the _land floe_ is ice attached to the land. _Field ice_ varies in thickness from 15 to 20 feet. On its surface there is a deposit of several feet of snow which melts in the height of summer, forming numerous fresh-water pools on the ice. Generally an ice-field is traversed by long ridges of _hummocks_, often 40 to 50 feet high, brought about by the collision of two fields, the irresistible pressure causing them to rise up.