FIELDS OF FORCE AND OF MASS IN THE SEA. 



[ 45 



other, and vice versa. If both kinds of charts be drawn, care must be taken 

 that they be not interchanged. The best distinction between them will be this: 

 The figures added to the curves on the topographic charts are all a little below a 

 certain decimal number, thus 9.74, 19.46, 29.20 . . . , while the figures on the 

 isobaric charts are always a little above the same decimal numbers, as 10.26, 20.57, 

 30.91 .... 



In figs. 30 and 31 we have, finally, two sections containing the profile curves of 

 the isobaric surfaces drawn simply as horizontal lines, and those of the surfaces of 

 equal anomaly of the specific volume. These give, as we have developed on an 

 exaggerated scale, the elevations and depressions of the true isosteric curves, making 

 the intersection with the isobaric curves more conspicuous. The first is taken 

 across the Faroe Island bank, the second passes from the Baltic through the Belts, 

 along the Norwegian submarine channel across the Norwegian Sea, as shown by 

 the two lines on the station chart (fig. 29). The great density of lines of equal- 

 volume anomaly in the Belts is especially conspicuous. Here we have the change 

 from the brackish Baltic waters to those of the greater salinity of the open sea, and 

 at the same time the greatest deviation from the true equilibrium conditions. 



Corresponding sections containing the profile curves of the equipotential sur- 

 faces and the surfaces of equal anomaly of density would have had the same 

 appearance, the only difference being that the curves of equal-density anomaly 

 would run a little^closer together than those of equal-volume anomaly. 



2M0 



Anomaly of sp.vol. ''2200. lO^nf/ton 



tni.Mlnl t I I I > I I 



O 500 



J ,_! 



iOOOhm. 



Belts 



Baltic 



anomaly. Every parallelogram re presents o.oooi isobaric-isosteric unit-tubes. 



