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. 283 movement ? If so, many difficulties would vanish ; among them those which were first mentioned, and those perplexing anomalies on the south coast of New Holland." — (Jour. R. Geog. Soc. vol. vi. part II. p. 336.) It might have been concluded that these questions had scarcely- been noticed, as I heard nothing on the subject, had I not lately read the following remarks in a work pubhshed in 1837. Whether their author ever saw the questions, I do not know ; but as his observations bear strongly upon the subject, and are those of an eminent mathe- matician, I quote them verbatim :— " Suppose several high, narrow strips of land were now to encircle the globe, passing through the opposite poles, and dividing the earth's surface into several great, unequal oceans ; a separate tide would be raised in each. When the tidal wave had reached the far- thest shore of one of them, conceive the causes that produced it to cease ; then the wave thus raised would recede to the opposite shore, and continue to oscillate until destroyed by the friction of its bed. But if instead of ceasing to act, the causes which produced the tide were to re-appear at the opposite shore of the ocean, at the very moment when the reflected tide had returned to the place of its origin, then the second tide would act in augmentation of the first and if this continued, tides of great height might be produced for ages. The result might be, that the narrow ridge dividing the adja- cent oceans would be broken through, and the tidal wave traverse a broader tract than in the former ocean. Let us imagine the new ocean to be just so much broader than the old, that the reflected tide would return to the origin of the tidal movement half a tide later than before ; then instead of those two super-imposed tides, we should have a tide arising from the subtraction of one from the other. Tlie alterations of the height of the tides on shores so circumstanced might be very small, and this might again continue for ages, thus causing beaches to be raised at very diiFerent elevations, without any real alteration in the level, either of the sea or land." — (Babbage's Ninth Bridgewater Treatise, pp. 248, 249.) Additional data, and leisure to reflect upon them, have tended to confirm the view taken previously to asking those questions in the Geographical Journal ; but before stating this view more expUcitly, it is necessary to lay facts before my readers, from which they may judge for themselves. bb2