8 On M. Hansteen's recent Magnetic 



crosses the Equator near the western coast of Africa, as 

 shewn by my observations at the island of St. Thomas. 



We may hope that the further tracing of the curves, in the 

 Asiatic quarter, which have not been subject to M. Hansteen's 

 observations in Siberia, will ere long be accomplished by the 

 scientific industry of British officers employed in India ; where 

 a line through the British dominions, from Ceylon on the south, 

 to the Himalaya mountains on the north, would probably in- 

 tersect the curves designated respectively by 308, 321, 335, 

 and 351 seconds, nearly at right angles to their course. 



Mr. David Douglas, well known to you as the enterprising 

 traveller and successful naturalist, in the countries adjacent to 

 the Columbia river and its tributaries, returns in September to 

 the north-west coast of America, on an undertaking which will 

 occupy him there many months. He will be well provided with 

 instruments, and is practised in the modes of observation. He 

 hopes to determine the magnetic phenomena from California in 

 the south, to the furthest extent towards the north to which cir- 

 cumstances may enable him to prosecute his researches ; and 

 from the ocean on the west, occasionally to the Rocky moun- 

 tains on the east. He will probably ascertain the situation on 

 the western side of North America of the curves 287" and 

 297", and will approach 278", when at his eastern limits. 

 But it is from travellers in the interior of the United States, 

 and in the countries adjacent to the Slave lake and Coppermine 

 river, that we must expect exact determinations of this in- 

 teresting curve 278". Unquestionably, however, the space 

 included by the innermost curve is the field for observations of 

 the very highest importance on the subject of the magnetism 

 of the globe; and as it is traversed annually under the direc- 

 tion of the Hudson's bay Company, we may confidently hope, 

 from the ready disposition which that Company has shewn, in 

 so many instances, to promote scientific researches, that much 

 time will not elapse before that really important journey will 

 be performed by a person properly qualified, by previous 

 practice, to observe with the precision necessary on so parti- 

 cular an occasion. 



In regard to the great space in the northern hemisphere oc- 

 cupied by the Pacific Ocean, the numerous islands with which 



