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

1832. OBSERVATIONS CHRONOMETERS. 75 no more, until I had an interval of leisure, and a prospect of some cloudless nights. Having so many good chronometers on board ; being prac- tised in observations such as they require ; and placing great confidence in their results ; I felt inclined to give attention and time to them rather than to perplex myself, and cause much delay in moving from place to place, by attempting series of observations which would give occupation to an astro- nomer, and could not be undertaken by me, while actively engaged in coast-survey, without interfering with other duties. In the Appendix it may be seen how far results obtained by the chronometers agree with those of a higher class, especially with the recent ones of Captain Beechey, to whose determina- tions, resulting from moon-culminating observations, I con- clude that a high value will be attached, because he is a well- practised and able observer. As I found that a difference, exceeding four miles of longitude, existed between the meridian distance from Bahia to Rio, determined by the French expedition under Baron Roussin, and that measured by the Beagle ; yet was unable to detect any mistake or oversight on my part ; I resolved to return to Bahia, and ascertain whether the Beagle's measure- ment was incorrect. Such a step was not warranted by my instructions ; but I trusted to the Hydrographer for appre- ciating my motives, and explaining them to the Lords of the Admiralty. In a letter to Captain Beaufort, I said, " I have not the least doubt of our measurement from Bahia; but do not think that any other person would rely on this one measure only, differing widely, as it does, from that of a high authority — the Baron Roussin. By repeating it, if it should be verified, more weight will be given to other measures made by the same instruments and observers." We sailed with the ebb-tide and sea-breeze, cleared the port before the land-wind rose, and when it sprung up steered along the coast towards Cape Frio. Most persons prefer sailing from Rio early in the morning, with the land-wind ; but to any well-manned vessel, there is no difficulty whatever in working