Ml 



ATLANTIC OCEAN. 



ATLANTIC OCEAN. 



rtraiU lying between Trinidsd and the bland of Martinique. Between 

 Trinidad and Grenada it run* from 1 to 14 mile per hour; lest 

 between 8t Vincent and St. Lucia ; and between the latter island and 

 Martinique it ooune u reduced to 31 mile* per day. Farther to the 

 north, and especially at the Virgin Island, the Ma-water runs only 

 from S to 10 miles per day, and that u the common rate of the ilrift- 

 currcnt It may be said that the Ouyana current is lost in the Carib- 

 bean Sea, for in the latter no perpetual current has been observed. 

 The whole course of the Ouyana current may be reckoned at about 

 2500 nautical miles. 



The third branch of the equatorial current is the Eratil Current, 

 which branches off from the equatorial at 8 8. lat, opposite Cape 

 St. Augustin, at a distance of about 300 miles to the east of it. Between 

 the point where it branches off and 16 or 17 of S. lat it has consider- 

 able breadth, and does not approach the shores of South America 

 nearer than 260 miles. Afterwards it increases in breadth and velocity, 

 and approaches nearer the land. Opposite Cape Trio it is 200 miles 

 from the coast, and runs about 80 miles per day. As the shore south 

 of this cape falls off to the west, the current U at a greater distance ; 

 and though it soon changes its direction, it does not approach nearer 

 than 250 miles to the coast, off the mouth of the Plata River, running 

 all this way from 15 to 20 miles per day. It is crossed by the Plata 

 River, just as the Ouyana current by the Amazonaa River. Here too the 

 current of the river is observable in the sea at a distance of 600 miles, 

 but it seems not to have the least effect in changing the direction of 

 the stream-current, which continues, though much weakened, farther 

 to the south, and may be traced to the straits of Magalhaens and Le 

 Maire. As this current runs at a considerable distance from the shores 

 of Brazil, the intermediate space is occupied by other currents, which 

 mostly however follow the direction of the monsoons which blow along 

 this coast. 



The moit remarkable and at the same time the best known of the 

 Atlantic current* is the (/''/ Stream of the northern hemiaphe re. It* 

 origin is in the Oulf of Mexico, where the warm water which enters it 

 from the Caribbean Sea, between Cape Catoche and Capo St. Antonio, 

 by being subjected to a nearly circular rotation, and influenced pro- 

 bably by other OVUM* still unknown, is raised to a high degree of 

 temperature, the thermometer indicating 86, while under the same 

 parallel r<!f> N. lat) the ocean only shows 78. Two currents, which 

 put in motion perhaps three-fourth)* of the waters of the Oulf of 

 Mexico, unite about 60 nautical miles to the westward of Havannnh, 

 between thr hank of Isabella on the side of Cuba, and the Tortugas 

 on that of Florida Reefs ; and this union gives rise to the Oulf Stream. 

 In the beginning its course is not rapid, and along the shores of ( 'ul.a 

 it i* wesk, and Honitii0B nearly imperceptible : but it soon increases 

 in velocity, and before it enters the Strait of Florida nt the Salt Kays, 

 it runs 14 mile per hour on an average ; in the strait itself it acquires 

 a formidable swiftness. The Strait of Florida begins at the Salt Kays, 

 a reef lying 114 nautical miles to the north-fast of Havannah, and 

 extends thence to the northward, where it terminates between the 

 reefs of Cape Canaveral and the northern termination of the Loss or 

 Bahama Bank, at about 28 N. lat After entering this strait the 

 velocity of the Oulf Stream soon increases to 2J, 8, and occasionally 

 4 miles per hour ; but after running at this rate about 90 miles it 

 arrives at the Narrow*, where, between Cape Florida and the liii.iini 

 Islands (a small group belonging to the larger group of the Bahamas), 

 the strait is only 44 miles wide, and its water-way, by reefs and shoal*, 

 is *tritied to 864 miles. Here the mean velocity of the current is 

 nn limir ; and in the month of August 5 miles per hour, and 

 seldom below 5 through the remainder of the strait, which towards its 

 northern extremity widens to about 60 miles. In this course the 

 current has invented about four degrees of lat northward, but its 

 temperature is not sensibly diminished. A* it issue* from tl,. 

 of Florida the Oulf Stream is of a dark indigo 1.1m-. mid the line of 

 junction between it and the green waters of the Atlantic is distinctly 

 visible for some hundreds of miles. A* it proceeds northward the 

 lino n{ junction U lost to the eye, but it remains perceptible by the 

 thermometer for several thousand miles ; the waters of the A 

 coot-ding to Lieut. Maury, standing up like a cold wall on both nides 

 of the current 



laming from the Strait of Florida the Gulf Stream runs northward 

 along the shore* of Florida to 81 N. 1st, and afterward* nearly north- 

 aat along the shores of Georgia and of both Carolina*, as far as Cape 

 Hattera* (about 85 N. lot). In this course the current widens con- 

 siderably in breadth and decrease* in velocity and temperature. 

 Opposite the harbour of Charlcstown its breadth is from 60 to 68 

 miles; and at Cape Battens from 73 to 76 miles. At the latter place 

 iU mean velocity is only 3 mile* per hoar, and iU temperature ha* 

 fallen from 86* to 83. At Cape Hatteras the north-western or inner 

 edge of the currant is 24 miles louth-east of the cape. 



By the falling back of the cooct north of Capo Hatteras the current 

 direct, it* western edge towards the north, while the main body con 

 ttaae* iU former course to the north-east to a considerable distance. 

 At aiM.it 4i. N. lat it meet* the extensive Nantucket and St George's 

 banks, which turn it off seaward, and it never after approaches the 

 land. From this point it runs in the direction K. { N., brushing the 

 southern extremity of the Great Bank of Newfoundland, and it con- 

 tinual ia this UM to 4 and 44 long., and 87* and 48 lt Here 



however it bend* by degrees to the east, south-east, and south, and 

 having inclosed the island* of Floras and Corvo, which belong 

 group of the Azores, its traces appear in ordinary seasons to be lost 

 in the water of the ocean. Lieut Maury believe* however that he 

 has been able to trace it onwanU till " it finally meeU the 1 

 Islands. By these it is divided, one part going into the polar basin of 

 Spitsbergen, the other entering the Hay of Biscay, but each with 

 warmth considerably above ocean temperature." The trans) 

 West Indian seeds, tropical fruiu, to., to the western and northern 

 parts of Britain and Ireland, and even to the coast of Norway, is 

 undoubted ; and it is precisely to these ports that we must look for 

 the direction of the Gulf Stream if it reach the shores of Europe. 

 Investigations respecting the temperature of the sea* Kiini.imdiiiK 

 the British coasts and the character of the alga), Ac., have not I . 

 however been carried on to a sufficient extent, or in nul. u connected 

 manner, as to enable us to speak with certainty on thix by i 

 hence the British Association has presented a request to government 

 " to connect with the survey of the Oulf Stream an examination 

 zoology and botany of this current, and also of the temperature of tin- 

 seas around the shores of the British Inlands." 



In its ooune across the ocean, as it approaches the Azores, it U very 

 difficult to ascertain the breadth of the current, because the worm 

 water expands to the north and to the south to a considerable distance 

 in the sea, where no current can be traced ; in the former direction t<> 

 a degree or a degree and a half of latitude; and on the HI><. 

 even to two degrees and a half : it him been met with at 'M{ mi. I ". I 

 N. lat The strongest current is commonly met with between 88 and 

 39 N. lat : anil it is the opinion of many intelligent navigators that the 

 breadth of what may be called a current does not exceed 100 or rjn 

 nautical miles ; but the breadth of the current as well as of the belt 

 of warm water varies considerably at different periods. Its velocity 

 decreases gradually in its progress to the east Between the meridian* 

 of 66 and 66 it runs between 65 and 56 miles per day ; an. I :MIII 

 nautical miles farther to the cast from 30 to 38 miles. After it begins 

 to bend to the east and south-east its velocity diminishes more ra]>i.ily; 

 in the neighbourhood of the Azores its mean rate does not exceed 

 10 miles per day, having lost 20 miles per day in a course of 

 only COO miles. The temperature of its water likewise decreases 

 during all this course, but at a slower rate. For 600 nautical miles 

 from Cape Hatteraa, or under the meridian of 634 W. long., Ui. 

 mouieter shows 81 in summer, or from 104 to 114 above the water 

 of the ocean under the same parallel, after having traversed 4 degrees 

 of lat. Hence, to 424" N. lat. and 434 W. long., it loses 64 of heat, 

 the thermometer falling from 81 to 764. Thenoe to Corvo th. 

 mometer descends from 754 to 724, still preserving a temperature 

 of 8, or 10 above that of the oceun. 



Where the Oulf Stream brushes the Great Bank of Newfoundland 

 the warm water of the current is about 8 higher than that of tin- 

 ocean, but the water of the ocean exceeds that which covers the Great 

 Bank by 26. These different degrees of temperature, though existing 

 so near one another, con never attain an equilibrium, because > 

 them proceeds from a cause which is peculiar, and whose inflii. 

 the same time ia permanent To this difference of temperature the 

 fogs on the banks and the coast of Nova Scotia may be attributed. 



The whole course of the Oulf Stream, from the Salt Kays to the 

 south-west of the Azores, amounts to upwards of SOOii n:mtirnl miles, 

 in \\lii.-li !'. 1 1 rue it traverses from 19 to 20 degrees of lat. (23 to '- 

 43), and iliinini.-Oips in temperature 134 (from 86 to 724"). According 

 to Major Rennell it arrives at the Azores in 77 or 78 days. 



The Oulf Stream being itself of considerable breadth, and covering 

 besides with the warm water brought down by it large tracts of the 

 sea on both sides of it* course, forms a vast expanse of warm water 

 in the centre of the North Atlantic. It extends from the :tm:, 

 dian to the 75th, and sometimes covers in breadth at the eant end all 

 the sea from 33 or 84 to 45 N. lat., but at it* western extremity it 

 contract* to about 160 or 170 nautical miles. It is according! 

 miles in length, and at a mean 350 n. I. . in brnadtli, and t h.i 

 a more extensive surface than the Mediterranean Sea. This body of 

 water contains, besides the stream itself, its counter-currents, offsets, 

 overflowings, and deposits, the currant itself possibly not occupying 

 one-half of this space. The Mexican Sea may therefore be con- 

 as a vast cauldron for heating water, which is distributed over the 

 central parts of the North Atlantic. By the Oulf Stream the eastern 



i of tho Atlantic is kept free from ice, and a temperature . i 

 8* to 12 higher imparted to it than the water of the western side i.f thr 

 Atlantic in corresponding latitudes. Nor can it be questioned thn 

 a' vast expanse of warm water, from 8 to 10 above the temperature of 

 the ceo, mu*t have a great effect on the surrounding sea and the adjacent 

 countries ; and this influence no doubt reaches to the British J 

 and even to Norway, if the Oulf Stream really extends so far. But 

 to what extent these countries are influenced, or how for the influence 

 reaches, ha* not yet been fully elucidated. 



The surface of the Gulf Stream Lieutenant Maury describe* a* being 

 " n .!. ..il.le inclined plane, having the ridge or line of meeting of them 

 two planes near the axis of the stream, from which the surface water, 

 like tho rain from the roof of a house, runs off towards each 

 this ridge, he says, ha* been ascertained to be nearly two feet I 

 than the contiguous waters of the Atlantic. And to this peculiarity 



