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

Jan. 1830. compass affected — drawings. 388 ing to make no further use of a compass in this place ; and as Lieutenant Skyring might have been deceived in his bearings from a similar cause, I hoped to procure a round of angles, with a theodolite set to a true bearing, which might be serviceable for his work, as well as my own. Many pieces of the stone, from different heights, were brought down ; and in most of them were traces of metal. " The peaked top of this mountain is a mere heap of loose stones of all sizes. Whether the rock has been shattered in this manner by frost, by volcanic fire, or by lightning, I cannot tell ; but I should think, from its appearance, by all three. Many of the stones are vitrified, and many are porous, like pumice-stones, although not so light. " 20th. I again went up Mount Skyring, taking a theodolite with me ; and as the day was perfectly clear, and free from clouds, every point of land was visible, which can at any time be seen from that summit. Mount Sarmiento appeared in all its grandeur, towering above the other mountains to at least twice their height, and entirely covered with snow. Having set the theodolite to a painted post, fixed on shore near the Beagle (five miles distant), from which I had previously obtained the exact astronomical bearing of the spot on which the theodolite was placed ; I obtained a most satisfactory round of angles, including most of the remarkable peaks, islands, and capes, within a range of forty miles from the mountain. The day was so fine, that it was not cold on the height, nor was there any wind to disturb the adjustment of the instrument. This business being completed, I returned on board with Mr. Wilson, who, during the time I was on the height, made some very good sketches. Even at this early period his draw- ings were becoming a valuable addition to the gleanings of our cruise, and their number increased fast ; for he took much pains with them, and produced not only good drawings, but most accurate delineations of the coast. " 21st. Fine weather for this climate. Mr. Murray returned in the whale-boat, having had a successful trip. " By shooting and fishing we obtained frequent change of