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

1834. CLIMATE — BANKS — TIDES. 339 summer the heat is scorching, but not sultry ; and in winter, though the weather is sometimes searchingly cold, especially during southerly winds, the air is always elastic and whole- some. Changes of wind are sudden, and cause rapid, though not very great, variations of temperature. Sometimes the sky is slightly or partially overcast, occasionally clouded heavily but on most days there is bright sunshine, and a fresh or strong westerly wind. The confluence of a continental torrent of fresh water, with great tides of the ocean, which here rise forty feet perpendicu- larly, has embarrassed the mouth of the Santa Cruz with a number of banks. They are all composed of shingle and mud, and alter their forms and positions when aff'ected by river- floods, or by the heavy seas caused by south-east gales. Into the entrance of the Santa Cruz, the flood-tide sets about four knots an hour ; one may say, from two to five knots, according to the time of tide, and the narrower or broader part of the opening ; and outwards, the water rushes at least six knots on an average in mid-channel. There are places in which at times, when acted upon by wind or unusual floods, it runs with a velocity of not less than seven or eight •knots an hour — perhaps even more; but near either shore, and in bights between projecting points, of course the strength of the outward as well as inward current is very inferior. In such a bight, almost under some high cliff's on the south- ern shore, the Beagle was moored, and it is easy to conceive the different views presented in this situation, with forty feet change in the level of the water. At high water, a noble river, unimpeded, moves quietly, or is scarcely in motion : at other times, a rushing torrent struggles amongst numerous banks, whose dark colour and dismal appearance add to the effect of the turbid yellow water, and naked-looking, black, muddy shores. The boats sailed on between some of the banks, with a fresh southerly wind, disturbing every where immense flights of sea-birds. Now and then a monstrous sea-lion lifted his un- wieldy bulk a few inches from the stony bank, lazily looked z2