THE GULF STEEAM. 395 



and divides them in proportionate times ; consequently it directs and in- 

 creases them, with an Easterly moon and wind to the West, and with a 

 Westerly moon and wind to the East ; so that the West and East shores 

 are at times deprived of, and at other times overflowed by, Tides, occa- 

 sioned by these vicissitudes. 



The boisterous East, N.E., and North winds, which affect the Gulf 

 Stream, generally begin in September, and continue until March ; when, 

 if the moon happens just at the time to be on the full or change, they 

 commonly end with a Hurricane. 



(387.) The United States Coast Survey authorities, in order to render 

 the investigations of their steamer Blake more reliable, decided in 1885 to 

 make the attempt to anchor this schooner-rigged vessel of 218 tons register, 

 along the axis of the Gulf Stream, and there make observations on its 

 Velocity, Temperature, &c., at various depths. This was successfully 

 accomplished, and much information added to our knowledge, a special 

 form of current meter being used, devised by Lieutenant Pillsbury.* 



Commander Bartlett, U.S.N., who was in charge of the Blake, between 

 1877 — 1880, before any attempt had been made to anchor in great depths, 

 came to the conclusion that 3 knots an hour was a general average to allow 

 for the whole Stream, but between the Bahamas and Florida, in the axis 

 of the Stream, it was as high as 5*4 miles an hour. 



Mr. Agassiz, who accompanied Commander Bartlett, states in his book, 

 mentioned in the note on page 352, that the Gulf Stream flows at the rate 

 of about one-fourth (sic) of a mile an hour through Yucatan Channel. 

 Through the Straits of Bimini it has a velocity of 4 to 5 miles, but this 

 velocity rapidly decreases as we go North. Off St. Augustine it is rarely 

 more than 4 miles ; from thence to New York it decreases to 2^ miles an 

 hour ; off the Banks of Newfoundland it is reduced to 1^ or 2 miles an 

 hour ; and at a distance of 300 miles to the Eastward the velocity of the 

 Gulf Stream, which has constantly been spreading out fan-shaped, is 

 scarcely perceptible. 



General H. Mathiesen, in the' work mentioned in the note on page 378, 

 states that from his researches he considers the mean velocity of the Gulf 

 Stream, throughout its course, to be about 58 miles a day, varying from 

 61 miles as a mean of January, February, and March, to 52-7 miles as a 

 mean of July, August, and September, 



(388.) Lieutenant Pillsbury's Investigations. — We have already men- 

 tioned, in the note on page 373, the valuable contribution to our know- 

 ledge of the Gulf Stream, drawn up by Lieutenant J. E. Pillsbury, U.S.N., 

 and we now proceed to give information gained from its perusal. 



During the spring and summer months of the years 1885 — 1889, the 

 steamer Blake was employed in making observations on six sections across 

 the Gulf Stream, as follow : — 1. Cape San Antonio to Yucatan Bank. 

 2. Across the extreme Western part of Florida Strait, near the meridian 



* A wire half-inch rope was used for this purpose, the length of rope used varying 

 with the bottom, current, and depth. In less than 600 fathoms two to three times the 

 depth was required, and in 2,000 fathoms 3,000 fathoms of rope was generally sufficient. 

 Slie could remain at anchor with the wind blowing at a force of 6 or more, unless with 

 a heavy sea. The deepest water anchored in was 2,180 fathoms. 



