NA TURE 



=)7- 



THURSDAY, OCTOBER i6, 1879 



POLAR ICE 



Die Metamorphosen dcs Polarciscs. Von Karl Weyprecht. 



(Wien, 1879 '■ Moritz Perles.) 



THIS book of Karl Weyprecht's is a most valuable 

 outcome of the Austro-Hungarian Arctic expe- 

 dition of 1872-1874, so well known already from the 

 interesting general popular account of the doings of the 

 expedition which has been published in most European 

 languages. In the present work the author confines him- 

 self to an account of the phenomena presented by the ice 

 amongst which he spent so many weary months. It 

 might well be supposed that a book treating of such a 

 subject only would be dull reading, but so graphic are 

 Lieut. Weyprecht's descriptions, and so pleasantly are 

 his long series of observations strung together into a 

 continuous whole, that his book is most entertaining 

 throughout, and the reader lays it down with a very much 

 enhanced comprehension of the never-ceasing changes 

 and mighty power of Arctic ice. Most of the facts re- 

 corded are known to Arctic explorers, and have been 

 more or less set forth by them in their various writings, 

 but no connected account of all the forms of the growth 

 and death, of the movements and struggles of bergs and 

 floes and ice of all forms has been before attempted 

 Lieut. Weyprecht tells it us all from his own observations. 

 The book is divided into a series of chapters headed as 

 follows : — I. Various Forms of the Ice and their Origin, 

 II. Ice-pressures. III. The Ice in Winter. IV. The 

 Ice in Summer. V. The Changes of the Ice. VI. The 

 Water Movement in the Polar Regions. VII. The Ice 

 Movements. VIII. The Ice of the Arctic Interior. 



In the first chapter he treats of the three different kinds 

 of Polar ice : glacier ice, salt-water ice, and fresh-water 

 ice. As an example of the mighty size of the Polar 

 glaciers, the parents of the icebergs, he cites the Hum- 

 boldt glacier of Smith Sound, which, pushing itself into 

 the sea in Smith Sound, forms an unbroken ice coast-line 

 composed of perpendicular cliffs 300 feet in height above 

 the sea-level, and 60 miles in length, a single solid ice 

 wall split only by vertical fissures. The fresh-water ice 

 is clear as crystal, and so hard that the Norwegian 

 walrus-hunters who run their small vessels in their voy- 

 ages against all other ice obstacles, of whatever size, 

 are careful not to charge even comparatively small 

 pieces of this. This kind of ice is, however, scarce in the 

 polar regions ; it is the third kind of ice, that of salt 

 water, or " field-ice," which forms by far the greater part 

 of floating ice, and with which the book is mainly con- 

 cerned. The Tegetihoff' was shut in for a year in field- 

 ice, and the author watched the incessant changes in the 

 ice with great care throughout this period. 



.\ simple smooth sheet of sea-water ice is no sooner 

 formed than it begins to be subjected to a variety of in- 

 fluences, which speedily convert its smooth expanse into 

 a complicated rugged surface, covered with ridges, 

 valleys, and irregularities of all kinds, render its thickness 

 everywhere unlike, and split it up with innumerable 

 fissures. Most important amongst the causes of these 

 changes are the variations of temperature to which the ice 

 is exposed from the variation of that of the water below 

 Vol,. XX. — No. 520 



and the air above, and which are more or less local, and 

 affect the ice differently wherever its thickness varies. 

 From these differences of temperature ensue complicated 

 strains in all directions, due to the unequal expansion 

 and contraction of the mass, and the ice is rent by the 

 tension ; to these forces is added the pressure of surround- 

 ing ice-fields, driven by the action of winds or currents ; 

 long fissures are formed, the edges of which grind together 

 with mighty force. After a while the edges separate, 

 and the water between pulsates with the throbbing of 

 the surrounding floes. Again they come together, and 

 forced against one another with ever-increasing power, 

 they are crushed and break up, huge blocks are piled 

 above on the ice-surface, resting at all angles upon one 

 another, and other huge blocks are forced under the ice 

 below. Hence the ice becomes rugged above, and by the 

 freezing to it of the blocks forced under water, equally so 

 below, the variation in thickness is increased, and with 

 it the amount of strains caused by variation of tempera- 

 ture. The drifting snow hangs against the ridges and 

 pinnacles on the surface, and forms banks and mounds 

 which not only increase the effects due to temperature by 

 protecting the areas on which they lie from change, but 

 also by their immense weight, combined with that of the 

 projecting ice-masses by which they are formed, press 

 down the ice which supports them, whilst the blocks 

 below in other regions press it up. Throughout the mass 

 gravity acts as a disturbant, no part being water-borne at 

 its natural level, the mass is strained, and gives way in 

 all directions, and fresh complications ensue. 



All these changes are accompanied by a noise. The 

 unlucky prisoner in the field-ice during the imposing 

 unbroken loneliness of the long Arctic night, when the 

 wind is calm, can hear the crackle of the snow under the 

 stealthy tread of the Polar bear at an astonishing distance, 

 and hear what a man, speaking loud, says at 1,000 metres 

 distance. It can, therefore, be well understood how the 

 sound of the ice-pressures must travel to his ear from 

 enormous distances. "Sometimes," the author writes, 

 "the noise of the ice movements was scarcely to be heard 

 —a mere murmur — and came to our ears as does the play 

 of the waves on a steep coast from the far far distance. 

 Sometimes it hummed and roared closer to us, as if a 

 whole column of heavily laden waggons were being drawn 

 over the uneven ice surface." In the sound were com- 

 bined all manner of noises caused by cracking, grinding, 

 falling of blocks, crushing, and many other phenomena 

 of ice-life. "It is astonishing how far and how clearly 

 every noise is conducted in the ice. The noise at the 

 very margin of the field on which we were seemed to 

 occur immediately at our feet. ... If we placed our ears 

 to the ice the sound was heard so loudly that we might 

 have expected the ice to open under our feet the next 

 moment. The whole dry ice covering was as a vast 

 sounding-board. Whenerer, as I lay down to sleep, I 

 placed my ear against the dry wooden ship's side, I heard 

 a humming and buzzing which was nothing else but the 

 sum of all the noises which occurred in the ice at great 

 distance from the ship." 



A curious fact is described by the author, that the sur- 

 face of an expanse of young salt-water ice on which no 

 snow has yet fallen is soft, so that the footstep is impressed 

 upon its white covering as in melting snow. This is to be 



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