24 MEMOEANDUM. 



" Sir ; Admiralty Office, 11th November 1831, 



" With reference to the order which my Lords Commission- 

 ers of the Admiralty have this day addressed to you, I am 

 commanded by their lordships to transmit to you a memoran- 

 dum, to be shown by you to any senior officer who may fall in 

 with you, while you are employed on the duties pointed out in 

 the above order. 



" I am, Sir, &c. 

 (Signed) " Geo. Elliot." 

 " To Commander Fitz-Roy, 

 ' Beagle' surveying vessel, Plymouth.'" 



" Admiralty Office, 11th November 1831. 

 " Memorandum. 

 " My Lords Commissioners of the Admiralty having ordered 

 Commander Fitz-Roy, of his Majesty's surveying vessel the 

 ' Beao-le,' to make surveys of various parts of the South Ame- 

 rican station, it is their lordships' direction that no senior 

 officer who may fall in with Commander Fitz-Roy, while he 

 is employed in the above important duties, do divert him 

 therefrom, or in any way interfere with him, or take from him, 

 on any account, any of his instruments or chronometers. 



(Signed) " Geo. Elliot." 



" Memorandum. 

 " A considerable difference still exists in the longitude of 

 Rio de Janeiro, as determined by Captains King, Beechey, 

 and Foster, on the one hand, and Captain W. F. Owen, Baron 

 Roussin, and the Portuguese astronomers, on the other ; and 

 as all our meridian distances in South America are measured 

 from thence, it becomes a matter of importance to decide be- 

 tween these conflicting authorities. Few vessels will have ever 

 left this country with a better set of chronometers, both public 

 and private, than the Beagle ; and if her voyage be made in 

 short stages, in order to detect the changes which take place 

 in all chronometers during a continuous increase of tempera- 

 ture, it will probably enable us to reduce that difference within 

 limits too small to be of much import in our future conclusions. 



