540 



Captain Spratt on the Undercurrent [June 15, 



" The mean quantity of salt for the current from the north was 15*994 

 per 1000 ; that for the current from the south 11*801 ; that for the period 

 when there was no current at all 13*342. Once a week a sample was taken 



from the bottom The mean of nineteen observations was 19*002, 



which is rather under than above the real mean, and proves that it is water 

 from the Kattegat which runs at the bottom of the Sound." 



" Experiments once a week, at Copenhagen, from 3rd March to 25th 

 April, 1852, gave as follows: — for the surface 15*845 per 1000 salt, for 

 the bottom of the harbour 1 7*546 ditto, which seemed to prove that the 

 undercurrent at that season reached Copenhagen." 



In page 222, Dr. Forchhammer also shows the salinity of the German 

 Ocean, the Kattegat, and Sound, and in the eastern and western parts of the 

 Baltic as follows : — 



" German Ocean, mean of six analyses, 32*823. In the Kattegat and 

 Sound the quantity of salt is very variable ; a northerly wind makes it 

 richer in salt than with a southerly wind. The mean of six analyses and 

 141 observations, in which only chlorine was determined, gives 16*230 per 

 1000, the maximum 23*243, and the minimum 10*869. In the Baltic the 

 salinity varies very much, and is of course less in the eastern than the western 

 portions. I found the mean 4*931 per 1000 salt, the maximum 7*481 be- 

 tween Bornholm and Sweden, the minimum at Kronstadt 0*610 per 1 000 salt." 



The relative saline densities are therefore as follows : — 



German Ocean 32*823 mean. 



Kattegat and Sound 16*230 „ 



Baltic 4*931 „ 



Baltic, between Bornholm and Sweden 7*481 maximum. 



Dr. Forchhammer' s observations are all upon the densities at different 

 depths in the Sound, and some few temperatures at the surface and bottom. 

 There were, unfortunately, none upon the rate of the surface-current in 

 descending depths, as carried out by me in the Mediterranean and Black 

 Sea Straits, or without doubt he would have found the same results, that 

 is, by the fact recorded by him of the density being greater at the bottom 

 of the Sound than at the surface, he would have ascertained a correspond- 

 ing diminution in the outward rate of current in descent from the surface. 

 But he has inferred, from the fact of there being a slight increase of den- 

 sity at the bottom of Copenhagen harbour, viz. of 17*546 at the bottom 

 and of only 15*845 at the surface, that there was necessarily an undercurrent 

 there from the denser water of the Kattegat and German Ocean ; for 

 he says that at Copenhagen the density was " For the surface 15*845 per 

 1000 salt, for bottom of harbour 17*546 per 1000, which seemed to prove 

 that the undercurrent at that season reached Copenhagen/' Thus quite 

 overlooking the remarks he has made upon fluctuations in the saline den- 

 sities produced at times, both in the Baltic and Kattegat, from the influ- 

 ence of winds, and forgetting, too, " that for twenty-four days out of the 



