KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 47. NIO 4. 



35 



used. Generally that difference of specific gravity between bottom- and surface-water 

 was about 0,02; in a couple of cases it was deterniined by direct weighing and found to 

 be from 0,016 to 0,030. It appears from the footnote of p. 32 that some advantage 

 might be derived from experimenting also with greater differences of density; hitherto, 

 however, this has not been done. 



In this paper I intend to mention two distinct types of experiments. 



I. The first type pretty nearly approaches to the theoretical circumstances. There 

 is salt-water reaching considerably above the hill with a somewhat thinner fresh-water 

 top-layer. 



II. The second experiment again is an imitation of a characteristic hydrographic 

 situation, that of the average Scandinavian Fjord. The circumstances previous to the 

 tide-generating pendulum having begun its work, are those shown by the diagram below. 



The left compartment represents the fjord, by means of the submarine barrier 

 partially shut up from communication with the ocean to the right. The fjord only contains 

 fresh-water, and this is flowing out across the barrier, spreading itself as a thin surface- 



Fig. 4. 



layer above the salt ocean-water. An interesting detail is the inclination of the boundary 

 to the right. That arrangement is easily effected by filling first the »ocean» with salt 

 water, till the surface of it just touches the apex of the ridge; then from the left end of the 

 tank the black fresh-water is poured in. Finally there will be no difficulty to add, by 

 means of a glass tube, some more salt-water from the right, which then, without any 

 salt-water crossing the ridge, will force the fresh-water somewhat leftwards. The inclined 

 surface, the analogon of which will be observed on every hydrographic section of a 

 fjord, will now be quite stable, because of the smallness of the gravitational forces ten- 

 ding to give it a horizontal position. 



This experiment II gives a characteristic example of a case where circumstances to 

 the right of the ridge are quite different from those to the left. 



An important variation of this second experiment is realised by using three diffe- 

 rent layers of water. Assume in the diagram above the black water to have an interme- 

 diate density between the density of the bottom- water and that of pure fresh-water; if 

 now a layer of fresh-water is carefully poured into the tank, we shall have our new 

 arrangement. To the right there will be clear bottom-water and clear surface-water, 



