G78 TIDES AND CUKRENTS. 



form. Beginning at a certain thickness, the ice is almost free 

 from salt. The upper strata, however, on account of the salt they 

 contain, attract moisture in a great degree, and form a tough, 

 leathery mass which bends under foot without breaking. This, 

 however, is only the case with new ice, as after a short time the 

 salt crystallizes out of the ice, and the surface covers itself with a 

 snowy layer of salt, sometimes reaching two inches of thickness. 

 Even in the most intense cold this layer retains so much moisture 

 that it makes the impression of a thaw ; only little by little, evapo- 

 ration and drizzling snow do their work, and the ice itself becomes 

 brittle. 



" In this way almost all the salt, which was frozen in, crystallizes 

 out, and is washed off and back into the sea by the melted water 

 in the next summer. The melted water at the end of the summer 

 is, therefore, almost free from salt, and has a specific gravity of 

 1 '005. It is evident that a smooth plane of ice, as is found on 

 sweet water, is a very rare occurrence in Arctic regions. 



" The astronomical observations while the ship was still drift- 

 ing were confined to determinations of latitude and longitude, the 

 latter by chronometers and correction of clocks, by lunar distances, 

 as often as opportunity served. In this only a sextant and a 

 prism circle with artificial horizon were used. When the ship 

 was lying still, a little 'universal' instrument was erected, and 

 the determinations of time, latitude, and azimuth were made with 

 this. The longitude was calculated from the mean of as many 

 lunar distances as could be observed during the winter ; they 

 were 210 in number. The azimuth of a base line 2,171 metres 

 long, measured by Lieut. Weyprecht with a Stampfer levelling 

 instrument, was determined with the universal instrument of the 

 magnetic theodolite. All this work was done by Ensign Orel, 

 Lieut. Weyprecht only taking a share in measuring lunar distances. 

 The determinations of locality Avere made without regard to tem- 

 peratures ; if the mercury of the artificial horizon was frozen, 

 blackened oil of turpentine was used instead. The winter quarters 

 were in latitude 79° 5V, and longitude 58° 56' E. 



*' Of the results of the meteorological observations, only some 

 general ideas can be given, as here figures alone decide. They 

 were begun on the day the explorers left Tromso, and were only 

 discontinued when they left the ship; thus they were made 

 during twenty-two months. Readings were taken every two 

 hours, and also at 9 a.m. and 3 p.m., therefore fourteen times 

 daily. The observers were Lieut. Brosch, Ensign Orel, Capt. 

 Lusina, Capt. Carlsen, Engineer Krisch (from autumn 1872 till 

 spring 1873), and Dr. Kepes (during the last two months only). 

 The direction as well as force of winds were noted down without 

 instruments. Lieut. Weyprecht thinks this method by far the 

 best in Arctic regions, as errors are more or less eliminated, 

 while when using instruments the constant freezing, drifting snow, 

 &c., produce errors that cannot be determined nor controlled ; be- 

 sides, any one who has been to sea for a short time will soon 

 acquire sufficient exactness in these observations. 



