August 1, 1892.] 



KNOWLEDGE. 



1S7 



their efforts in this direction, and not the least valuable of 

 their contributious to North Atlantic lore is the determina- 

 tion, with approximate exactitude, of its currents and 

 di-ifts. 



The general character of the drifts has been long known. 

 Drifted matter from the New World has been found cast 

 upon the shores of the Old since the days of Columbus. 



tracks are laid down on the chart published by the Hydro- 

 graphic office at Washington, and an examination of those 

 which are laid down on the accompanying sketch-map will 

 reveal at a glance the system of oceanic circulation in the 

 North Atlantic. 



The indraft into the Gulf of Mexico is clearly indicated, 

 as also is the di-ift of the icy Arctic current, which flows 



Explanation of sketch ihoirinif lottle-drtfls. — The arrow-heads eliow the s]Jot where (he buttle was thrown OTerboard. Con- 

 sequently, the line of drift followed will be from the arrow-head to the other unmarked end of the line. In drawing the drift-lines 

 some attention has been paid to already-obtained knowledge relative to their direetion. for it is not always eoiTect to assume that 

 the drifting objeet moves in a straight line from the comraencenient of its voyage to where it is picked up This is most noticeable iu 

 the drift marked A, B, the bottle following a course almost identical with the eastern and southern boundaries of the Sargasso Sea. 



The most remarkable drift on record is that effected by 

 the ship " W- L. White." This vessel, an American 

 schooner, was abandoned off Delaware Iiay during the 

 terrible snowstorm of 13th March, 1888. She drifted 

 across the Atlantic, assisted doubtless by wind as well as 

 set of current, and finally stranded, after a voyage of 5000 

 miles, upon one of the outer Hebrides. From March 13th, 

 1888, to .January 23rd, 1889, was the time occupied on 

 this drift. About 1760 a.d., an English man-of-war was 

 wrecked near St. Domingo, and her mainmast was after- 

 wards found stranded on the shores of the Pentland 

 Firth. 



Such instances as these, however interesting they may 

 be, afford but little detail of the set of the ocean currents. 

 These details a bottle-chart issued by the United States 

 Marine Authorities supplies to a very material extent. 

 The plan adopted is the throwing overboard of bottles iu 

 which is a record of the ship's name, latitude and longitude, 

 and date. Of course the co-operation of the masters of 

 the merchant vessels trading to the United States is neces- 

 sary. The number of bottles which are traced bears but 

 a small proportion to the numbers thrown overboard, but 

 still they are sufficient to enable pretty accurate courses to 

 be assigned for the ocean currents. Seventy-five bottle- 



equatorwards along a course lying to the westward of that 

 followed by the Gulf Stream. The track of the Gulf 

 Stream from Newfoundland is almost coincident with the 

 fiftieth parallel of latitude. Looking at the eastern portion 

 of the chart, it will be seen that the existence of a powerful 

 indraft from the north-west into the Bay of Biscay and its 

 enclosing shores is clearly demonstrated. It is the failure 

 to recognize aright the influence of this current during the 

 prevalence of south-westerly winds that has led to so many 

 ships being cast ashore in the vicinity of Cape Finisterre. 

 Of these disasters that of H.M.S. Serpent was the most 

 terrible, but the current is a veritable danger-trap to ship- 

 masters given to corner shaving, as the records of wreck 

 enquiry courts show but too plainly. 



The bottle-chart shows an elliptical area of ocean water 

 whose principal axis lies along the thirtieth parallel of lati- 

 tude, and this area is identical with the Sargasso Sea. From 

 the incipience of Transatlantic voyaging down to the past 

 few years, our knowledge of this sea has remahied almost 

 stationary. Columbus discovered it, and commented upon 

 it, and the nautical world has since been content with his 

 description, and has added but little to it. He reported 

 pretty fully upon the pntdeiias de yerva, or seaweed 

 meadows, which the Santa Maria encountered, and subse- 



