Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.1): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

50 wiLT.i\s^\ws. Feb. 1827. tlie scenery greatly, particularly in the winter season : the north shore is also well wooded for about two-thirds up ; but the sum- mit is barren and the outline very much serrated, as is usual in slate formations. On the north shore we noticed some extraordinary effects of the whirlwinds which so frequently occur in Tierra del Fuego. The crews of sealing vessels call them ' williwaws,' or ' hur- ricane-squalls,'' and they are most violent. The south-west gales, which blow upon the coast with extreme fury, are pent up and impeded in passing over the high lands ; when, increasing in power, they rush violently over the edges of precipices, expand, as it were, and descending perpendicularly, destroy every thing moveable. The surface of the water, when struck by these gusts, is so agitated, as to be covered with foam, which is taken up by them, and flies before their fury until dispersed in vapour. Ships at anchor under high land are sometimes suddenly thrown over on their beam-ends, and the next moment recover their equilibrium, as if nothing had occurred. Again a squall strikes them, perhaps on the other side, and over they heel before its rage : the cable becomes strained, and checks the ship with a jerk, that causes her to start a- head through the water, until again stopped by the cable, or driven astern by another gust of wind. At all these anchorages, under high land, there are some parts more exposed than others ; and by watching for those places which are least troubled by these squalls, a more secure, or rather a more quiet, spot may be selected. I do not consider ships so anchored to be in danger if their ground tackle be good ; but every thing that offers a stiff resistance must suffer from the fury of these blasts. In many parts of this country trees are torn up by the roots, or rent asunder by the wind ; and in the Gabriel Channel the 'williwaws' bursting over the mountainous ridge, which forms the south side of the channel, descend, and striking against the base of the opposite shore, rush up the steep, and carry all before them. I know of nothing to which I can better compare the bared track left by one of these squalls than to a bad broad road. After