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

APPKNDIX. 298 the turn of stream for the time of high water, and registering or calculating observations erroneously, that little dependence can be placed in at least one-third of those hitherto recorded. On this account chiefly, though partly to simplify the question, I have not hoped to be much nearer the mark than half an hour in this dis- cussion, discarding fractions as much as possible, and attempting only to avoid errors of material consequence. Looking at the Atlantic, as represented on a globe, we see that Newfoundland and the adjacent coasts are so placed as to receive tidal impulses from the Arctic Sea, North Atlantic Ocean, the tropical part of the North Atlantic and the gulf stream : besides which, no doubt, a derivative from the equatorial zone is felt there. It is high water at the east side of the Atlantic, from the Canary Islands to Scotland, within an hour or two of the same time, on the salient points of the coast, namely, at about 4h. ; and if the opposite coast were straight, like that of Chile, and uninfluenced by derivative tides or by currents, we might expect that it would be high water there at about 7h., allowing that the tide-wave moved as it is found to do generally. But it is high water at about Ih., from 30° to 40,° the times increasing northward from 40° N. to the Bay of Fundy, and also increasing southward from 50° N. to that bay, where, as every sailor knows, the tides rise higher than in any other part of the world. Tliis sequence of times, each ending in about 43° N., the adjacent gulf stream, (an immense river in the ocean), and an accumulation of water in that corner higher than is known any where else, show that we cannot there expect to find data for tidal niles. In that quarter is evidently a marked exception, caused by the conflux of at least two primary tides, two derivatives, and a poweiful current, aided by the peculiar configuration of the land. In the Mediterranean it is supposed by many persons that there is no ebb and flow ; but Captain Smyth, who surveyed so much of its shores, informs me that he found a tide, small certainly and appa- rently not governed by the moon, but regular. I have myself noticed a small rise and fall there ; and the cun-ent, caused by tide, in the Faro of Messina, is well known. As the moon passes over the Indian Ocean, the natural eff^ect of her attraction must be to accumulate the waters, and draw the wave so caused after her, as in other places ; but while that ocean is obey-