390 OBSERVATIONS ON THE CUERENTS. 



are depths to which the Gulf Stream has little or no influence, as shown 

 by the Temperatures taken by H.M.S. Challe^iger, hereafter quoted. 



(381.) Velocity. — As would naturally be expected, from the difficulty of 

 making accurate current observations from vessels in motion, there is great 

 divergence between various observers as to the Velocity of the Gulf Stream. 

 We consider it better, therefore, to repeat much that appeared on this 

 subject in the previous editions of this work, and to give, in conclusion, 

 the results recently obtained from the United States Coast Survey steamer 

 Blake, when at anchor in various parts of the Stream's course. 



Our knowledge of the velocity of the Gulf Stream is not sufficiently ex- 

 tensive to pronounce absolutely at what rate it flows as a mean for the 

 whole year. It is very irregular in all parts, and there has been no sys- 

 tematic collection of observations recorded on the subject ; those inves- 

 tigated show there are more variations than can be reconcilable with the 

 change of the seasons. It is stated that the latter part of the month of 

 August and beginning of September is the period in which it attains its 

 greatest strength and highest temperature, and it is weakest and lowest 

 in February, but fluctuates in all seasons according to circumstances. The 

 strength of its Western and Northern borders, in its entire and vast extent, 

 is much greater than those on the East and South, which have invariably 

 a tendency to spread over the ocean in whirls or eddies, and are, therefore, 

 comparatively weak. 



Major Eennell estimated the Gulf Stream to move in the Narrows at 

 from 82 to 96 and 120 miles per day. A more rigid calculation of his and 

 other older data gives 65-4 miles per day as an annual average. This last 

 estimate is much reduced by the investigation carried out by the Meteor- 

 ological Office in 1872, which gives a mean annual rate of only 48 miles 

 per day. The investigations carried out by the United States authorities 

 appear to confirm the earlier figures. 



(382.) Captain Livingston stated : — " The calculations of the velocity of 

 the Gulf Stream are not to be depended on. I have found it setting at the 

 rate of 5 knots, and even upwards ; this was on the 16th and 17th of 

 August, 1817. On the 19th and 20th of February, 1819, it seemed to be 

 almost imperceptible. In September, 1819, it set at much about the rate 

 described in the charts." 



One remarkable instance of its diverging from the usually supposed velo- 

 city is given in a communication of Captain Giles, of the barque Charles, 

 who found it to run 5 and 5^ knots, in January, 1843. " The first day I 

 began to make any material progress was with the Tortugas bearing about 

 S.E. ; the following day I had a current of 53 miles S.E. by S. ; the next 

 day, 60 miles S.S.E. i E. I was then in lat. 24° 10', long. 83° W. The 

 weather would not permit our sighting the Tortugas, though we passed 

 them very closely. The next day we made, by very good observations, 75 

 miles of due Easterly current, which, with the ship's work, placed her in 

 lat. 24° 12', long. 81° 33' W. The succeeding day, towards dark, the wind 

 being strong from E.S.E., and considering myself in the vicinity of the in- 

 draught of the Great Inlet, I put the ship's head to the Southward, under 

 close-reefed topsails, and nothing more set, and reached her to till daylight, 

 that being twelve hours good. Towards noon it fell calm ; I then fovmd 



