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

318 BELLACO ROCKS — RKFEACTION. Jan. At low-water there are but eight feet on this rock, which is not far from mid-channel, just without the entrance. We anchored near Watchman Cape, and in other places along the coast, before reaching Port San Julian, and some time was devoted to an examination of the BeUaco Rock and its vicinity, as there is a dangerous reef extending from Watch- man Cape towards, but not quite out to the Bellaco. In my own notes I find this rock mentioned as " almost covered at times, but occasionally showing above water as high as the hull of a ship !" In Mr. Stokes's journal, left with me, it is mentioned in these words : " Passed between the Bellaco Rocks, close to the eastern one, nearly a-wash ;" and in the diary of the NodaW voyage (in 1619), it is spoken of as " una baxa que lababa la mar en ella," which means, a rock a-wash. The rise of tide there is about twenty feet, which explains the various appearances it had to my eye ; for at high water I saw it almost covered, or a-wash ; and as the Nodales described it similarly in 1619, there can have been extremely little, if any, change in the relative heights of sea and land in this place during the last two hundred and fifteen years.* Some time ago I thought differently, having formed a hasty opinion upon the fact of my having seen the rock as high out of water as a ship's hull. I did not then consider how much the tide falls, nor did I recollect, till I referred to notes, that I had also seen it a-wash (the top almost level with the water), at times during the many days we were in the neighbourhood. On the day that Mr. Stokes and myself made our respective notes on the Bellaco (without any communication of opinion), an extraordinary effect of refraction was remarked. The meri- dian altitude of the sun (then far south) observed at opposite horizons, differed no less than sixteen miles ! Similar effects had been noticed before, especially on the Patagonian coast, therefore we generally observed both ways ; but to nearly * As the larger and eastern rock is about a hundred yards long and eighty wide, with kelp growing on most parts of it, I do not think the top can wear away while so protected by sea-weed.