I2 o HYDROGRAPHY. 



lying stations in the section a high maximum temperature combined with a very small degree of 

 salinity. In station 103 where the ice-water layer is thickest, the lowermost isotherms o°o and o°5 go 

 highest; we have thus here the lowest temperature. 



SECTION XVII. 



From station 109 in an easterly direction. 



The isohaliue 35-00 is drawn in reference to very unreliable data, so that we cannot draw any 

 conclusions from its form, but only from its existence and position, which shows that we have again 

 here ice-water with an under-layer in the same manner as before. The uppermost o° isotherm is a 

 curve open to the eastward, so that the section is too short to enable us to come to a conclusion 

 concerning the extension of ice-water to the eastward. It is evident, however, from other reasons that 

 station 105 cannot be far from the eastern limit of the ice-water. The lower o° isotherm is namely at 

 the highest in station 106, and from there it is sinking rapidly to the eastward. The increasing 

 thickness to the eastward of the stratum of water whose temperature is above o°, is most likely due 

 to the presence of- the warm water of the eastern part of the Northern Sea. In the western part of 

 section XVII, a stratum is found in the deep with a very small degree of salinity and a proportio- 

 nally high temperature, and similar to the layer in the former section. 



The sections XIV, XV, XVI and XVII have in so far as regards position one feature that is 

 common to all of them, and this is, that they all extend in a north-easterly and easterly direction 

 from the eastcoast of Iceland^ and that they are all lying completely in Polar-water. This can be seen 

 by the fact of the uppermost stratum of water, the upper layer, having a smaller salinity in the sections 

 than 35-00, and for the greater part a very low temperature. 



From the curves, plates XII — XVI, will be seen that the temperature at the surface, as a rule, 

 is 4 — 6°. It is decreasing slowly until it reaches a depth of 10—20 fathoms (19 — 38 metres), from which 

 depth it goes down rapidly, most frequently below o°, to the freezing-point of the sea-water, and 

 reaches its minimum value at a depth varying between 20 and 50 fathoms (38 and 94 metres). From 

 this depth the temperature rises, sometimes rapidly and sometimes slowly, till it attains its maximum 

 value, which is not equally great, and can be found at different depths, most frequently between 50 

 and 100 fathoms (94 and 188 metres). The stratum of water in which the temperature is increasing, 

 may be regarded as a layer of transition between the upper and the under-layer. 



Owing to the fact of the observations being rather incomplete, it is attended with more diffi- 

 culty to lay down general rules concerning the variation of the salinity in the upper-layer. The com- 

 mon feature, however, seems to be that the salinity is smallest, though much varying, at the surface. 

 It changes but little at the upper 10 — 20 fathoms (19—38 metres), and grows very rapidly till a depth 

 of about 30 fathoms (57 metres), where it attains its maximum value between 34-50 and 34-90. From 

 this maximum, the salinity goes down to a minimum, and rises again to a maximum value, which is 

 the largest value of the salinity at all station-determinations, most frequently larger than 35-00. The 



