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

•28 MEMOKANDUM. would be permitted. Where so many unforeseen circumstances may disturb the best-concerted arrangements, and where so much depends on climates and seasons with which we are not yet intimately acquainted, the most that can be safely done is to state the various objects of the voyage, and to rely on the Commander's known zeal and prudence to effect them in the most convenient order. " Applying this principle to what is yet to be done in the Strait, and in the intricate group of islands which forms the Tierra del Fuego, the following list will show our chief desi- derata, " Captain King, in his directions, alludes to a reef of half a mile in length, off Cape Virgins, and in his chart he makes a seven fathoms' channel outside that reef; and still further out, five fathoms with overfalls. Sarmiento places fifty fathoms at ten miles E.S.E. from that Cape; thirteen fathoms at nineteen miles ; and, at twenty-one miles in the same direction, only four fathoms, besides a very extensive bank projecting from Tierra del Fuego, between which and the above shoals Malas- pina passed in thirteen fathoms. In short, there is conclusive evidence of there being more banks than one that obstruct the entrance to the Strait, and undoubtedly their thorough exami- nation ought to be one of the most important objects of the Expedition; inasmuch, as a safe approach to either straits or harbours is of more consequence to determine than the details inside. '• None of the above authors describe the nature of these shoals, whether rock or sand ; it will be interesting to note with accuracy the slope, or regularity, of the depths, in their different faces, the quality of their various materials, and the disposition of the coarse or fine parts, as well as of what species of rock in the neighbourhood they seem to be the detritus ; for it is probable that the place of their deposition is connected with the very singular tides which seem to circulate in the eastern end of the Strait. " Beginning at Cape Orange, the whole north-eastern coast of Tierra del Fuego as far as Cape San Diego should be sur-