May 24, 1858.] PHYSICAL GEOGRAPHY— CURRENT CHARTS. 
329 
Current Charts. — Mr. A. G. Findlay lias constructed an excellent 
chart of the North Atlantic Ocean, on fonr sheets, which embodies in 
a condensed form the results given in the extensive series of charts 
published by the American Bureau of Hydrography, as well as other 
authorities. This chart, intended for the use of sailors, will show 
the connexion between the different branches of the meteorology 
of the sea, the similarity between the circulation of the air and 
water over its area, and their effects on the temperature in different 
seasons. Among the results it appears that the great mass of 
waters takes about one year to travel from the Bay of Biscay to 
the Gulf of Mexico, while the more rapid circulation of the smaller 
volume from the Mexican Gulf, by the Gulf-stream, occupies about 
eight months in reaching the shores of Europe. These periods, 
derived from a careful calculation of all attainable observations, 
accord very closely with that of the drift of bottles, a collection of 
which, made by Capt. Becher, r.n., shows that the currents are not 
so rapid as has been usually considered. 
The Gulf-stream ceases to be a marked current after passing 
eastward of the Newfoundland Banks ; its warm waters are then 
drifted to the east and north-east by the prevailing south-west and 
west winds, by which cause its effects are propagated to Britain 
and the coast of Norway. 
In 1838 Mr. AY. 0. Bedfield propounded the theory, that the 
Arctic currents, after passing over the Banks of Newfoundland, 
flowed beneath the Gulf-stream to the southward and south-west- 
ward — a theory which has been confirmed by American navigators, 
who have found that at a depth of 370 fathoms, or bed of the Gulf- 
stream, in its narrowest and warmest part, the temperature is at 
zero. This remarkable and exceptional phenomenon does not, 
however, extend eastward of 46° AY. meridian ; for Commander 
Dayman found in that longitude that the water had a temperature 
of 39°‘7,* at a depth of 1000 fathoms, in two instances, showing a 
remarkable contrast in so small a distance. 
The Arctic current had been considered to be lost at Cape Hat- 
teras, in its south-west course ; but the cold bands which have been 
observed by the American surveyors to exist in the Gulf-stream 
must be derived from this source. There is another curious subject 
for consideration — the peculiar configuration of the coast of the 
* 39*5° is the temperature assumed by Sir Jas. Ross as that at which sea- water 
has its maximum density. — Voyage to the South Pole , ii. 156, 375, 384. 
2 C 2 
