THE GULF STEEAM. 401 



have frequently found an eddy-current setting to the Westward from 1 to 

 1^ mile per hour. After passing the Tortugas, I have invariably felt a 

 Southerly Current until I had reached the longitude of 84° 30' W., and 

 even further that this at times, particularly in November, 1848. 



" Eeturning from New Orleans, I have always made it a point to 

 keep to the Westward until I had reached longitude 85°, latitude 28°, 

 before keeping off. My object in doing this is, that the Wind here 

 generally prevails from the Northward and Eastward, and that the 

 Current generally sets to the Southward and Eastward, which generally 

 facilitates the passage. After rounding the Tortugas, with the wind from 

 the Eastward, I have generally beat down on the Florida side, knowing 

 that the strongest Current prevails on that shore, unless too close in. 

 From Carysfort Eeef to Matanilla, I have always endeavoured to keep in 

 the middle of the Stream. During all my voyages, I have made it a rule 

 to steer N. by W. from Matanilla to latitude 22°, and then North to 

 latitude 31°, before hauling up N.E. by N. ; by so doing I have, with a 

 few exceptions, kept the strongest current. On some other occasions, I 

 have hauled up on a N.E. by N. course, when in lat. 30°, long. 79° 40', and 

 have soon found myself on the Eastern edge of the Gulf Stream. After 

 rounding Cape Hatteras, it is advisable to keep to the Westward, especially 

 in the winter season, on account of the prevailing Westerly winds." 



(390.) Surface Temperature. — The high temperature of the Gulf Stream 

 is one of its chief characteristics, and has attracted from very early times 

 almost as much attention as its velocity. Some remarks on this subject 

 will be found in previous pages. A work, entitled " Thermometrical 

 Navigation," written by Colonel Jonathan Williams, was published at 

 Philadelphia, 1799, from which the following extracts are given. It will 

 be seen, however, from what is stated later on, that the thermometer 

 cannot be regarded as a completely reliable guide to its navigation. 



Commodore Truxton says : — " In the Stream the water is much warmer 

 than the air ; indeed, I have known it 10° warmer ; but as soon as you get 

 within the Stream (that is, between it and the coast), the water becomes 

 colder than the air ; and the more as you get on soundings, and approach 

 the shore. If mariners, who have not the opportunity of determining 

 their longitude by celestial observations, will only carry with them a good 

 thermometer, and try the temperature of the water, and compare it with 

 that of the air every two hours, they may always know when they come 

 into or go out of, the Gulf Stream. Indeed, I have always made a prac- 

 tice, when at sea, of comparing the temperature of the water and air 

 daily, and often very frequently, during the day, throughout the voyage ; 

 whereby I immediately discovered anything of a current that was going, 

 and afterward found its strength and direction by observations for the 

 latitude and longitude. It is of the utmost consequence in making a 

 passage to and from Europe to be acquainted with this Gulf Stream ; as, 

 by keeping in it, when bound Eastward, you shorten your voyage; and by 

 avoiding it, when returning to the Westward, you facilitate it incon- 

 ceivably ; so much so, that I have frequently, when bound from Europe 

 to America, spoke European ships, unacquainted with the strength and 



N. A. 0. 52 



