Page:Physical Geography of the Sea and its Meteorology.djvu/429

Rh that, in my mind, admits not of so easy solution, especially 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 6° 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 warm 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 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 when he comes to cast up his reckoning the next day at noon, he remarks with surprise that no current has been felt.

752. Humbolt's 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 perfectly calm, there appear on its surface narrow belts, like small rivulets, and in which the water runs with a noise very perceptible 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 N.E.; others E.N.E., although the general motion of the ocean, indicated by a comparison of the log and the longitude by