Page:A Voyage of Discovery and Research in the Southern and Antarctic Regions Vol 1.djvu/72

6 of Pico Ruivo, 6097.08 or 6102.90 English feet, according as Gay Lussac's or Rudberg's measure be taken for the expansion of air by heat. The result is computed by Bessel's tables, in which the hygrometric state of the atmosphere at the two stations is taken into the account. This elevation is some hundred feet greater than the height which was assigned by Lt.-Colonel Sabine from barometrical observations made by the late Captain Clavering, R.N., and himself, in the winter of 1821–22. It is probable that this difference has been occasioned by the frequently practised deception of the guides: when fog conceals the highest peak from view, they halt at a station they call the "Homme à pied," which, under such circumstances, may be easily mistaken for the summit, having a steep descent on every side. By this artifice the guides save themselves and the travellers the trouble and fatigue of descending into a deep ravine, and of thence ascending the most toilsome portion of the journey to the peak.

Since this was written, the result of Lieutenant Wilkes's observations has been published in his Narrative of the United States' Exploring Expedition. His computations assign an elevation to Pico Ruivo above half-tide of six thousand two hundred and thirty-seven feet: a difference of nearly one hundred and forty feet from our observations, and much greater than we should expect