Observations in Siberia. 9 



it is interposed present points of observation of easier access 

 than many parts of the respective continents. A commence- 

 ment has already been made by Captain Lutke, commanding 

 one of the Russian ships of war at present engaged in a scien- 

 tific voyage. In a letter which I have received from him, 

 dated from New Archangel (Norfolk Sound) in July, 1827, he 

 has been so obliging as to communicate to me the results of 

 several observations on the Magnetic Dip and Intensity, which 

 he had found opportunities of making in his passage from 

 Conception. I have not availed myself of these in the accom- 

 panying sketch of the isodynamic curves, because I regard his 

 communication as private until he shall have returned and 

 made his own observations public. At the date of his letter he 

 was on the point of sailing for Behring's strait and Kamtchatka, 

 which voyage, as well as in his subsequent operations, he will 

 doubtless have obtained results of great interest. 



If we now direct our attention to the southern hemisphere, 

 we find nearly the whole field of enquiry untrodden. Of pub- 

 lished observations, there are only those made by M. de Ros- 

 sel, in the voyage of D'Enlrecasteaux, at Java, Amboyna, and 

 Van Diemen's Land. Of observations made, but not yet pub- 

 lished, there are, 1st, those of Captain de Freycinet, at several 

 stations visited by the expedition under his command : of these 

 no public account has yet, I believe, been given : 2d, those 

 which are at present in progress by Captain King, who is en- 

 gaged in the survey of the southern parts of South America. 

 The results obtained by him in the first year of his survey have 

 been received in England : they commence at Rio Janeiro, and 

 are continued at intervals down the eastern coast as far as Port 

 Famine : he will probably have since extended them to Con- 

 ception on the western side, the limit of his survey in that quar- 

 ter. The results transmitted will require some slight modifica- 

 tions on his return to this country, to compensate for differences 

 of temperature, &c. : but none that can interfere with their 

 general effect in evidencing a progressively and rapidly increas- 

 ing intensity, from the neighbourhood of Rio, where it corre- 

 sponds with the curve marked 370" in the accompanying 

 sketch, to the Straits of Magellan, where it is intermediate 

 between the intensities designated by 278" and 287". The 



