July, 1891. 
THE GULF STREAM. 
159 
ON THE GULF STREAM AND ITS EFFECT UPON 
THE CLIMATE AND PLANTS OF ENGLAND AND 
NORWAY.* 
BY W. P. MARSHALL, M.I.C.E. 
The Gulf Stream is the most important of all the ocean 
currents, both on account of its great extent, and of the 
remarkable effect that it produces in actually changing the 
climate of a portion of the world. It is well known bv name 
from books on geography, but is not at all realised until 
actually seen, as I found when crossing the Stream in the 
passage to America, and subsequently in witnessing its effects 
upon the climate and plants of Norway. The Gulf Stream 
takes its name from the Gulf of Mexico, from which the 
stream starts; and it travels the whole length of the North 
Atlantic Ocean, a distance of 5000 miles, to the North Cape, 
the northern extremity of Norway. 
The Gulf Stream has its origin in the great Equatorial 
Current which follows the sun across the Atlantic, from the 
Coast of Africa to the Gulf of Mexico, a distance of 7000 
miles, and is considered to be produced by the action of the 
Trade Wind upon the surface of the ocean, the Trade Wind 
being a wind constantly blowing from east to west in that 
region, following the sun. 
The Equatorial Current is a comparatively shallow surface 
current, not extending deeper than about 300 feet, and 
flowing with a moderate speed of about three quarters of a 
mile an hour ; but when it enters the contracted passage 
between the West Indian Islands and the main land, the 
velocitv of the current increases considerablv, and it then 
sweeps completely round the Gulf of Mexico, from which it 
issues as the Gulf Stream at a velocitv of three to four miles 
«/ 
an hour. The temperature of the Equatorial Current is about 
82°, and the water is further heated up to 88° in the hot 
caldron of the Gulf of Mexico. The stream is about 50 
miles wide on leaving the Gulf. 
The temperature of the Gulf Stream is still as high as 84° 
when opposite the southern part of the United States, where 
the stream extends to about 150 miles’ width, and opposite 
New York the temperature is 77°, and the width is extended 
to nearly 300 miles. The stream crosses the Atlantic, 
sweeping past the British Isles, where its average temperature 
is still as high as 50°, and a remarkable effect is produced in 
* Read before the Birmingham Natural History and Microscopical 
Society, April 16th, 1889. 
