I hope you will not regard the illustration as too familiar, if I remind you that in the economy of a household pipes of hot water are sometimes employed in tempering the atmosphere by heat carried from below to rooms above. In the economy of Nature these thermal currents are only pipes of hot water, modifying the climate of continents by carrying heat from the warm cisterns of the South into the most distant places of the North. So also there are sometimes pipes of hot air, having a similar purpose; and these, too, are found in this region. Every ocean wind, from every quarter, traversing the stream of heat, takes up the warmth and carries it to the coast, so that the oceanic current is reinforced by an aërial current of constant influence.
These forces are aided essentially by the configuration of the Northwest Coast, with a lofty and impenetrable barricade of mountains, by which its islands and harbors are protected from the cold of the North. Occupying the Aleutian Islands, traversing the peninsula of Alaska, and running along the margin of the ocean to the latitude of 54° 40´, this mountain-ridge is a climatic division, or, according to a German geographer, a “climatic shed,” such as perhaps exists nowhere else in the world. Here are Alps, some of them volcanic, with Mount St. Elias higher than Mont Blanc, standing guard against the Arctic Circle. So it seems even without the aid of science. Here is a dike between the icy waters of Behring Sea and the milder Southern Ocean. Here is a partition between the treeless northern coast and the wooded shores of the Kenaians and Koloschians. Here is a fence which separates the animal kingdom, having on one side the walrus and ice-fox from the Frozen Ocean, and on the other side the humming-bird from the tropics. I simply report the testimony of geography. And now you will not fail to observe how by this configuration the thermal currents of ocean and air are left to exercise their climatic power.
One other climatic incident here is now easily explained. Early navigators record the prevailing moisture. All are enveloped in fog. Behring names an island Foggy. Another gives the same designation to a cape at the southern extremity of Russian America. Cook records fog. La Pérouse speaks of rain and continued fog in the month of August. And now visitors, whether for science or business, make the same report. The forests testify also. According to physical geography, it could not be otherwise. The warm air from the ocean, encountering the snow-capped mountains, would naturally produce this result. Rain is nothing but atmosphere condensed and falling in drops to the earth. Fog is atmosphere held in solution, but so far condensed as to become visible. This condensation occurs, when the air is chilled by contact with a colder atmosphere. These very conditions occur on the Northwest Coast. The ocean air, coming in contact with the elevated range, is chilled, until its moisture is set free.