454 



THE YERMAK ICE BREAKER. 



ship itself, her three propellers giving facility for such complicated 

 maneuver. The tioat passed under the chain of ridges, but of course 

 it did not get to the lowest part, which might project somewhere. 

 Often the sounding tube has shown 4 to 5 fathoms' depth, but some- 

 times it has shown 7 fathoms. Separate pieces may project below to 

 the depth of 8 or 9 fathoms, so that the ice tioe may touch the ground 

 at that depth, but probably will not properly settle itself until the 

 depth of 5 or 6 fathoms is reached. 



Hydrological observations consisted in determining the specific grav- 

 ity of water at diti'erent depths. Below I give the specific gravity and 

 temperature of water at two stations, one being on a parallel of the 

 north part of Spitzbergen, another on the parallel of North Cape: 



On examining the figures of both stations, one can not fail remai'k- 

 ing that from the depth of 100 fathoms to the ])ottom the temperature 

 and specific gravitj^ of water are almost the same. In the upper 

 strata of station No. 34 the water on the surface is the same as at the 

 l)ottom. visible gulf stream water; while at station No. 31 the water 

 of the upper strata is much influenced by fresh water from ice and 

 precipitations. It is remarkable that on that station the superficial 

 water is cold; then comes a warm laj^er, then again cold, then warm 

 and cold again. 



Cold water at the lower strata at both stations has a temperature 

 of 30°. Such a low temperature is not met in the Atlantic to the 

 south of the Thomson ridge. The water acquires such a low tem- 

 perature somewhere in these localities; it can not be in the polar sea, 

 notwithstanding its excessive cold, because the upper strata there 

 have less densit5\ I have discussed this question with Sir John Mur- 

 ra3^ He thinks that the cold layer of this region is supplied from 

 the top water being cooled during the winter somewhere close to Spitz- 

 bergen, or to the south of it, where no water of less density interferes 

 with the upper layers descending to the bottom, when it is properh^ 

 cooled b}' the winter cold. I perfectly coincide with the opinion of 



