Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2- Appendix): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

APPENDIX. 291 very different times ; and that the high water of the northern zone will have passed that meridian about three hours before the equato- torial wave. Impulses derived from them might succeed one another at an intermediate point, such as the Sandwich Islands. Besides which, there is the tide of their own zone to be considered in consequence of which alone it might be high water at about 6 : thus these islands are so situated as to receive at least three tides one primary and two derivative — whose respective times of high water are 1, 6, and 10, a succession which may well be supposed to neu- tralise any ebb, and maintain the water thereabout above its natural level, independent of tide. About the Strait of Magalhaens, and along the eastern coast of Patagonia, there are very high tides ; apparently complicated, but perhaps less so than is usually beheved. A powerful tide arrives at the Falklands, and at the east end of Staten Land, at about 9 ; which is opposed by another powerful tide arriving from the west. The union of these two accumulates the water between Tierra del Fuego and the Falldands, and on the east coast of Patagonia. Within the Strait of Magalhaens, westward of the Second Nar- row, it is high water at about 4.40, and the tide rises six feet but eastward of the First Narrow it is high at 1.30, and the tide rises forty feet. Now, as in one case the sea only rises three feet, and in the other twenty, above its mean level, every one would expect to find a rush of water through the Narrows, from the high sea to the low, and such is the fact. From ten to four the water runs westward with great velocity, and from four till ten it rushes eastward. During the first interval, from ten to four, the eastern body of water, between Tierra del Fuego and the Falldands, is above the mean level ; and during the latter interval, from four till ten, it is below the mean level — that which it would have if there were no tides. From 50° S. to near Blanco Bay in 40° S. the tide-wave certainly travels along the coast to the north ; but this is a derivative from the meeting of tides above-mentioned, combined with the primary tides on the coast traversed. In this way principally may we account for a high tide in one place on this coast, and a low one on another (similarly situated, though differing in latitude) ; and, again, a high tide at another place. During the twenty-four hours that the deri-