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APPENDIX. 



ments of water never reached. That they were caused by wind I 

 proved by the logs of ships, which were in the respective gales at 

 the time their effects on the sea were thus felt at a great distance. 

 The places to which I particularly allude are the Cape Verde Islands, 

 Ascension, St. Helena, Tristan d'Acunha, Cape Frio, Tierra del 

 Fuego, Chiloe, the coast of Chile, the Galapagos Islands, Otaheite, 

 the Keeling Islands, Mauritius, and the Cape of Good Hope. 



Waves, or rollers, caused by earthquakes, or volcanic eruptions, 

 are, of course, unconnected with wind or atmospheric pressure. 



But in accounting for currents, as occasioned in some if not many 

 instances by tidal pressure, or a succession of tidal impulses, we 

 must not overlook the well known power of wind in giving horizon- 

 tal motion to water, as weU as in elevating or depressing it. 



Wind blowing almost always in one direction is known to com- 

 municate a movement to waters, and it is remarkable that the gene- 

 ral movements of the North Pacific as well as the North Atlantic 

 are from west by the north to east, or, as a sailor would say, * with 

 the sun while in the southern oceans. Pacific, Atlantic, and Indian, 

 they are generally * against the sun,' or from west to east by the 

 south — ^both corresponding to the general turn of the winds in the 

 respective hemispheres. The Chile current after coasting Peru, 

 preserves a temperature of about 60° up to the Galapagos, and there 

 it meets a warm stream out of the Gulf of Panama, at a tempera- 

 ture of about 80°. The two unite together and turn westward 

 along the equatorial zone. There is a remarkable exception on the 

 east coast of Patagonia, where the current sets northward, owing, 

 probably to tides. 



I cannot end this imperfect attempt to sketch out some of the 

 movements of ocean, without reminding young readers to whom 

 the subject may not be so familiar as it is to others, that there may 

 be circulations of water in a vertical direction, or in a plane inclined 

 to the horizon, as well as horizontally : and that bodies of water 

 differing in temperature, as well as in chemical composition, do not 

 hastily blend together. Their reluctance to mix is observable at sea, 

 when we sail out of one current, or body of water, into another — 

 differing perhaps in temperature, chemical composition, and colour. 

 At the meeting, or edge, of such bodies there is usually a well 

 defined line, often considerable ripplings, which indicate some degree 

 of mutual horizontal pressure — as of separate masses'. 



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