OBSERVATIONS CHllOKOMETEKS. 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 



