HYDROGRAPHY. IO( - 



SECTION I. 



In an east and westerly direction south of Iceland. 



The salinity from all the determinations that are represented in the sections I, II. Ill and IV, 

 does not vary much. If is to be observed, however, that in section number I an observational error will 

 have the effect of being able to alter the nature of the isohaline 35-25 entirely. It seems, however, to be 

 evident that there is a rise towards the westward. It appears distinctly from section I, and specially 

 from the curves appertaining thereto, that the salinity is least at the bottom and remarkably small 

 in station 46 and 47, where the temperature likewise is low. 



The temperature at the stations 45 and 46 decreases rapidly at the bottom, and the bottom- 

 temperature at station 46 even goes down as far as 2°4, that is to say, lower than in the deepest 

 stations in section I, notwithstanding the fact that the depth in section 46 only is 720 fathoms 

 (1356 metres). We see thus that the bottom-water at the eastern stations in section I has a low 

 temperature and but little salinity, and this applies likewise specially to station 42 with a temperature 

 of o°4 and a salinity of 3495, as well as to station 43 with a temperature of o°i. That all the eastern 

 stations south of the Faroe-Iceland ridge have such a low temperature and such a small salinity at 

 the bottom, can only be accounted for in this way, that water has been running over the ridge 

 in a southerly direction. There is, as we know, water in possession of the aforesaid properties 

 north of the ridge. This layer of cold and not very salt bottom-water, which thus has passed over 

 the ridge, is undoubtedly not very thick. What has led to this supposition is, that the stations 44 — 45. 

 which are close to the stations 42 — 43, certainly show a low temperature and salinity at the bottom, 

 but by no means so small values for these quantities as the stations 42 — 43, and this assumption is 

 corroborated if we look at section XXIII. The circumstances are perhaps so, that but a small quantity 

 of the bottom-water can make its way over the ridge from the North, on account of the very small 

 differences of pressure, and that only a small part of it preserves its distinctive features in the recesses 

 of the bottom near the ridge. 



Taking apart these special circumstances at the bottom, the isotherms in section I follow a 

 nearly parallel course, specially in so far as regards the deep strata. The specific gravity is nearly 

 constant in a plan parallel with the surface, so that the whole of this body of water remains in a very 

 stationary state. The isotherm 8° goes deepest towards the east, so that the thickest warm 

 stratum of water, with its small specific gravity, is found on top of the coldest 

 bottom-water with the greatest specific gravity. Thus the strata of water would try to 

 settle, if no other causes exercised any influence, and the currents that exist independent of small 

 local differences of pressure, must therefore be of such a nature that this equilibrium is not disturbed; 

 the thickest warm stratum of water must therefore constantly be found at the eastern stations, and 

 this can be effected thereby, that the water at this place is running with a greater 

 velocity to the northward from warmer areas of the sea than is the case farther to 

 the westward, and likewise thereby that the surface-layer is running from west to 

 east. Both things may perhaps be the case. The isotherms 5 . 6° and 7° rise somewhat at station 75. 

 The water is thus colder here in equally deep strata, which likewise will be seen to be the case in a 

 still higher degree, the farther we advance to the westward. 



The Ingolf-Expedltion. I. 2. 14 



