198 THE GULF STREAM. 
Coast Survey all this has disappeared, and the lighting of the great 
highway of the Straits of Florida has reduced to a minimum the dan- 
gers of navigation, though the Tortugas are still a favorite resort, even 
in broad daylight, for old ships properly insured. 
The captain of one of the Spanish vessels was carried south, off the 
coast of South America, by the current which sweeps from Cape St. 
Roque along the shores of Brazil, and involuntarily discovered the Bra- 
zilian shore current. Though these different currents were known to 
exist in the Atlantic, the most crude notions of their origin and course 
prevailed. (Fig. 3.) According to Columbus, at the equator the waters 
of the ocean moved westward with the heavens above, rolling over the 
fixed earth as a center. It was only in the seventeenth century that 
physicists began to suspect a connection between the currents and the 
rotation of the earth, a view afterwards maintained by Arago and Hum- 
boldt. 
The first scientific basis for the exploration of the Gulf Stream was 
undoubtedly due to Franklin. At the time he was Postmaster-General 
of the colonies, his attention was called to the fact that the royal mail 
packets made much longer passages to and from Europe than the trad- 
ing vessels of Massachusetts and Rhode Island. On talking the mat- 
ter over with Capt. Folger, of Nantucket, he first learned the existence 
of astrong easterly current, of which the New England captains took 
advantage in going to Europe, and which they avoided by sailing a 
northerly course on the home voyage. Folger also called Franklin’s 
attention to the fact that this current was a warm one.* He and Dr. 
Blagden becoming interested in the question, Franklin set out to ascer- 
tain the size of the current and its temperature. Soon after, Franklin 
published the first chart of the Gulf Stream (Fig. 4), for the benefit of 
navigators, from information obtined from Nantucket whalemen, who 
were extremely familiar with the Gulf Stream, its course, strength, and 
extent. 
From the time of Franklin until the problem of the Gulf Stream was 
again attacked, in 1845, by Franklin’s descendant, Prof. A. D. Bache, 
of the United States Coast Survey, many ingenious theories were 
published, but nothing was added to our knowledge of the origin and 
structure of the Gulf Stream. Humboldt, Arago, and others attempted 
to trace in the Gulf Stream a secondary effect of the trade-winds, and 
of the rotation of the earth. The officers of arctic expeditions sent to 
Spitzbergen did not fail to see the effect of a mass of warm water 
passing northward, and Von Baer was among the first to consider this 
body of water as an eastern extension of the Gulf Stream. Meanwhile 
the arctic explorers of Baffins Bay and western Greenland found them- 
selves baffled in their efforts to reach high latitudes by the powerful 
* It was noticed by Lescarbot, in 1605, that far north there was a mass of warm 
water moving toward the east, and that both north and south of it the water of 
the Atlantic was cooler. 
