HYDROGRAPHY. l2q 



of the section, is making its way in underneath the Atlantic-water, a distribution which is a conse- 

 quence of the circumstances relating to the specific gravity. 



SECTION XXIII. 



Abreast of the Faroe-Iceland ridge. 



This section shows the transition between Atlantic-water and Polar-water. It 

 will be seen that the isotherms are rising considerably from south towards north, and that the 35-25 

 isohaline goes from the surface down to the bottom close to the top of the ridge. That the transi- 

 tion from one species of water to the other must take place very abruptly, appears 

 from the fact of the isotherms lying close to one another. 



The Faroe-Iceland ridge is thus the boundary between Atlantic-water and 

 Polar- water, and not only between the strata of water which are actually debarred 

 from one another by the ridge itself, but also in so far as regards the strata that 

 are lying in a higher position. When it is said here that the ridge forms a boundary 

 between the two different species of water , this is to be understood so , that there is water — on 

 each side of this ridge — which is in possession of specially characteristic qualities, and that water is 

 not flowing across the ridge in so large qtiantities that it is able to efface the boundary between 

 the two species of water, or remove it in any appreciable degree, or make its form subject to any 

 alteration of importance. 



It has been said on page 105 that water is flowing across the ridge from north to south. The 

 same appears from this section, as the isotherms for the lowest temperatures in the Atlantic are 

 stretching along the bottom and down the south western side of the ridge. The body of the cold, 

 and in consequence of this heavy Polar-water, which is making its way in underneath the water of 

 the Atlantic, is, however, so small, that it is only in the proximity of the ridge that the 

 presence of it can be proved with certainty; farther west it can be traced, as, in consequence 

 of the influence of the Atlantic, its distinctive features have nearly been effaced; that is to say: its 

 low temperature and little degree of salinity. 



It appears from the salinity at the surface in section XXIII, that ice-water is found at 

 the stations 135, 137 and 139. At station 136, the salinity is specially high, and at station 138 medium, 

 from which can be seen that the confines for the extent of the ice-water must have a 

 very irregular form. It appears likewise from this, that the ice-water is stretching 

 a great distance to the southward towards the Faroe Islands. 



SECTION XXIV. 



From station i in a west north-westerly direction. 



Station 1 is in common with the two sections XXII and XXIV, which are situated in such a 

 manner that they form a little angle with one auoher, section XXIV south of section XXII. They 

 are both lying along the Faroe-Iceland ridge, but while the western part of section XXII is stretching 

 into the Polar-water, the same does not apply to section XXIV. 



The Ingolf-Expedition. I. 2. *7 



