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Page:Popular Science Monthly Volume 35.djvu/702

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THE POPULAR SCIENCE MONTHLY.

ure expended in arctic exploration, so little is known and so many of the popular ideas are erroneous.

Most arctic travelers will agree in saying that careful study of all the works on the subject will form but a meager preparation for a prospective explorer. It is a new world; impressions are so strange and vivid that no fixed plan of description will suffice.

In the narrow Greenland waters each successive headland, island, or mountain stands as the mark of farthest progress and blasted hopes of brave old-time navigators. Can anything be more pathetic than the quaint log-book of that stanch old seaman. Captain John Davis, with its account of protracted struggles and final disappointment? He sailed in the time of Raleigh and Blake. Now, but a few miles beyond a black, ram-shaped cape, that he named Sanderson's Hoop, lies the Danish trading post of Upernavik, and every summer ten powerful steam whalers smash through the ice, which at this point turned back his small sailing vessels. For hundreds of years, dating back to the time of Davis and Frobisher, the art of ice navigation has been constantly improving, until now it is a very rare thing for either a Dundee whaler or a St. John sealer to meet with serious disaster while pursuing its legitimate calling.

With our own Bering Sea whalers the case is different—there are important differences between the ice encountered in Greenland waters and that north of Alaska. A description of the circumstances affecting the formation of the various kinds of berg and floe ice will make this clear.

The natural form of an iceberg is a regular prism, broken from the face of the glacier as its onward motion forces it down along the bottom of the inclosing fiord, by the buoyant action of the water. Through the tides the upward pressure of the water varies constantly, and has much to do with the production of internal strains and fissures, which form planes of cleavage parallel to the face of the glacier; one of these ultimately marks the boundary of the berg, the others are weak spots which may develop afterward. Where glaciers approach the sea at a steep grade, they move more rapidly, are subjected to greater stresses, there is less opportunity for the exhibition of the viscous property of ice at the freezing-point, débâcles occur more frequently, and the bergs are smaller and more irregular. Under such conditions the ice is full of partly cemented cracks and curved fissures, so that in a short time water-markings, ice-scorings and scratches, and the melting of snow-spots, produce the most fantastic and airy shapes. More durable than clouds, they still rival them in variety of design and change of form, as successive beauties are revealed in passing. Apparently free from all the requisitions of