142 The National Geographic Magazine 



actual position of the vessel at noon 

 the second day is at B. In this case 

 B'B will be set down in the log as the 

 current experienced during the inter- 

 vening 24 hours. In case no astronom- 

 ical observations can be obtained, as 

 happens in fog or cloudy weather, the 

 position by dead reckoning has to be 

 adopted as the best obtainable, with 

 the result that if such weather con- 

 tinues for several days in succession, 

 as sometimes happens at certain seasons 

 of the year, the true position of the vessel 

 may differ considerably from the assumed 

 position, which is frequently accompa- 

 nied with disaster upon approaching 

 shore. To lessen this danger these cur- 

 rent charts have been constructed, giv- 

 ing the results of current observations 

 in the past, and the master of a vessel, 

 by reference to them, is able to profit by 

 the experience of those who have sailed 

 over the same waters in previous years, 

 and to some extent correct his own dead 

 reckoning. 



The current charts of the various 

 oceans published by the British Admi- 

 ralty — the charts which are universally 

 employed by navigators — are the result 

 of many, many thousands of observa- 

 tions — in fact, of all the reliable current 

 observations taken since 1830. A glance 

 at these charts will make plain the dif- 

 ficult}' which confronts the navigator 

 when approaching a dangerous coast, 

 such as that of Newfoundland or of 

 France, and compelled to rery upon his 

 dead reckoning. 



For a knowledge of the motions of the 

 water throughout longer periods of 

 time we are forced to depend upon the 

 drift of floating objects, derelicts, wreck- 

 age, floating bottles bearing messages, 

 and the like. Two attempts recently 

 made to study the currents of the sea 



by this method deserve mention. The 

 first is an effort to obtain a knowledge 

 of the currents in the Arctic Ocean. 

 Stout oaken casks, each one numbered 

 and bearing a message, have been dis- 

 tributed by the Philadelphia Geograph- 

 ical Society among the whalers bound 

 for the Arctic by way of Bering Sea, 

 where they winter in the vicinity of the 

 mouth of the Mackenzie River. These 

 casks are to be placed upon the ice as 

 far eastward as circumstances permit, 

 and the expectation is that the}- will 

 enter the Atlantic either by Davis Strait 

 or Barents Sea, be noticed by passing 

 vessels, and picked up. A letter from 

 Dr. Bryant, the president of the society, 

 states that 35 out of the 50 casks have 

 been alreadj r set out, and that in his 

 opinion the}' may be looked for on the 

 o'ther side of the circumpolar area about 

 a year from the spring of 1902. 



The second project is the proposed 

 investigation of the current in the 

 neighborhood of Ushant and Finisterre 

 by means of floating bottles. This has 

 been undertaken b}' Lloyds, the great 

 ship underwriting firm, and has prob- 

 ably been brought about by the number 

 of vessels lately lost in that vicinity, 

 owing to the fact that they were out in 

 their reckoning. The bottles, which 

 are of gutta-percha, are to be sealed and 

 thrown into the sea bj' passing vessels, 

 each one containing a label showing the 

 date and the position at which it was cast 

 adrift. They are then supposed to drift 

 ashore and to be recovered. The ex- 

 pense involved is considerable. On the 

 bottle it is stated that a reward of five 

 francs will be paid for the return to any 

 of His Majesty's consuls — an instance 

 of liberality of expenditure in the acqui- 

 sition of knowledge which is almost 

 unprecedented. 



