TIDE-RIPS AND SEA DRIFT. 403 



blem that, in my mind, admits not of so easy solution, esjDecially 

 if my suspicions are true in regard to the northerly set. I shall 

 look with much interest for a description of the ' currents ' in 

 this part of the ocean." In latitude 38° south, longitude C^ east, 

 he found the water at 56^. His course thence was a little to the 

 south of east, to the meridian of 41° east, at its intersection with 

 the parallel of 42^ south. Here his water thermometer stood at 

 50°, but between these two places it ranged at 60° and upward, 

 being as high on the parallel of 39° as 73°. Here, therefore, 

 was a stream — a mighty " river in the ocean " — one thousand six 

 hundred miles across from east to west, having water in the 

 middle of it 23° higher than at the sides. This is truly a Gulf 

 Stream contrast. What an immense escape of heat from the 

 Indian Ocean, and what an influx of warm water into the frozen 

 regions of the south ! This stream is not always as broad nor 

 as wann as Captain Grant found it. At its mean stage it conforms 

 more nearly to the limits assigned it in the diagram (Plate IX.). 



751. Commotions in the sea. — Instances of commotions in the 

 sea at uncertain intervals are not unfrequent. There are some 

 remarkable disturbances of the sort which I have not been able 

 wholly to account for. Near the equator, and especially on this 

 side of it in the Atlantic, mention is made, in the " abstract log," 

 by almost every observer that passes that way, of " tide-rips," 

 which are a commotion in the water not unlike that produced by 

 a conflict of tides or of other powerful cuiTents. These " tide- 

 rips " sometimes move along with a roaring noise, like rifts over 

 rocks in rivers, and the inexperienced navigator always expects 

 to find his vessel drifted by them a long way out of her course ; 

 but when he comes to cast up his reckoning the next day at noon, 

 he remarks with surprise that no current has been felt. 



752. HumholcWs description of tide-rips. — Tide-rips present their 

 most imposing aspect in the equatorial regions. Humboldt met 

 some in 34° N., and thus describes them : " When the sea is per- 

 fectly calm, there appear on its surface narrow belts, like small 

 rivulets, and in which the water runs with a noise very percep- 

 tible to the ear of an experienced pilot. On the 15th of June, in 

 about 34° 36' N., we found ourselves in the midst of a great 

 number of these belts of currents ; we were able to determine 

 their direction by the compass. Some were flowing to the Is .E. ; 

 others E.N.E., although the general motion of the ocean, indi- 

 cated by a comparison of the log and the longitude by chrono- 



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