401 THE PHYSICAL GEOGRAPHY OF THE SEA. 



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 currents. 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 

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

 remarks with surprise that no current has been felt. 



752. Tide-rips present their most imposing aspect in the equa- 

 ir.imboidt's descrip- torial regions. Humboldt met some in 84° N., 

 tionoftide-ripg. ^^^ ^-^^^^ dcscribcs 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 percepti- 

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

 about 34° 86' N., we found ourselves in the midst of a great num- 

 ber of these belts of currents ; we were able to determine their di- 

 rection by the compass. Some were flowing to the N.E. ; oth- 

 ers E.N.E., although the general motion of the ocean, indicated 

 by a comparison of the log and the longitude by chronometer, 

 continued toward the S.E." It is very common to see a mass of 

 motionless water crossed by ridges of water which run in differ- 

 ent directions. This phenomenon may be observed every day 

 on the surface of our lakes ; but it is more rare to find partial 

 movements impressed by local causes on small portions of water 

 in the midst of an oceanic river occupying an immense space, 

 and moving in a constant direction, although with an inconsider- 

 able velocity. In this conflict of currents, as in the oscillation of 

 waves, our imagination is struck with these movements, which 

 seem to penetrate each other, and by which the ocean is incessant- 

 ly agitated. 



753. Horsburgh, in his East India Directory, thus remarks on 

 Horsbui^h'a. them, whcu Speaking of the northeast monsoon 



about Java: "In the entrance of the Malacca Straits, near the 

 Nicobar and Acheen Islands, and between them and Junksey- 

 lon, there are often very strong ripplings, particularly in the 

 southwest monsoon ; these are alarming to persons unacquainted, 

 for the broken water makes a great noise when the ship is pass- 

 ing through the ripplings in the night. In most places ripplings 

 are thought to be produced by strong currents, but here they are 



