The universal geography : earth and its inhabitants

18 THE NOETH-EAST ATLANTIC.THE BALTIC.The Skager Eak communicates through the Kattegat with the Baltic, which,like the North Sea, is an inlet of the North Atlantic, though differing from itboth in the composition and general character of its waters. The word Baltic,probably of Lithuanian origin, as well as the island of Baltia mentioned byPliny, is said to mean " wdiite," in reference to its short and foaming crests. Bythe Germans it was called the East Sea when its southern shores were occupied bythe Slavs, and this designation, true as regards Denmark alone, has remained thegeneral name of this inland sea.It may in some resrjects be considered as an affluent of the Atlantic, to whichit contributes much more than it receives in return. The Neva, Niemen, Vistula,Oder, and the two hundred and fifty other streams of all sizes discharging into theBaltic, send down a volume of water far in excess of what is lost by evaporation.The amount has not yet been directly ascertained, but judging from the meansnow and rain fall of the entire basin, its normal increase may be set down at16,000 cubic yards per second. The whole of this excess must escape to theAtlantic through the Sound and Great Belt, for the level of the Baltic is not, as wastill lately supposed, higher than that of the North Sea. An outflowing currenthas accordingly been detected, running constantly from Copenhagen and Elsinoreto the Kattegat, except when neutralised, or even reversed, by the north winds.*Nevertheless the currents flowing from the Baltic do not fill the entire depthof their outlets. As in the Dardanelles and Bosporus, there is a smaller backflow of more saline and consequently heavier water, which is distributed throughoutthe basin of the Baltic. But for this circumstance the Baltic would, in thecourse of a few centuries, lose its brackish character and become a large riverbasin, presenting the appearance of an ocean inlet, but forming no part of it.The chemical analysis of the water taken from various depths has determined theexistence of the lower back currents in the Sound and Great Belt, constantly renewingthe saline properties of the Baltic.In the Great Belt, Meyer, Mobius, Karsten,andHensen have ascertained that the upper and fresher current is 10, the lower andmore salt counter-stream nearly 30 fathoms deep.tThe hydraulic works undertakenin the harbour of Copenhagen and the Sound have also afforded an opportunity ofdirectly measuring the saline back flow. It has often been observed that oftwo sailing vessels stemming the surface current in the Sound, here muchshallower than in the Great Belt, the larger has much the advantage, being aidedunderneath by the opposite stream to which its hull penetrates.Although the salineness of the great basin is thus constantly maintained, stillthe gulfs farther removed from the Atlantic receive but a small quantity of salt,the currents growing less and less brackish as they advance from the Skager Eak* Course of the upper current in the Sound for 134 days :From the Baltic to the North Sea86 days.From the North Sea to the Baltic 24 „Li .......... equilibrio 24 „Forchhammer and Prosilius, Philosophical Transactions, 1S65.t " Expedition of the Pomerania," 1871.