Magnetism of the Earth. 151 
Gulf of Guinea, in the northern hemisphere; and in the southern 
hemisphere, at the Island of Ascension, and at Bahia on the coast of 
razil. 
We may hope that the further tracing of the curves, which have 
not been subject to M. Hansteen’s observation in Siberia, will ere 
long be accomplished in the Asiatic quarter, by the scientific indus- 
try of British officers employed in India; where a line through the 
British dominions, from Ceylon on the south, to the Himalaya Moun- 
tains on the north, would probably intersect Nos. 5, 6, 7, and 8, 
nearly at right angles to their course. 
r. David Douglas, well known to you as the enterprising travel- 
ler 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 farthest extent to- 
wards the north, to which circumstances may enable him to prose- 
cute his researches ; and from the ocean on the west, occasionally to 
the Rocky Mountains on the east. He will probably ascertain the 
situation on the western side of North America, of the curves 3 and 
4, and will approach No. 2, when at his eastern limits. But it is 
from travellers in the interior of the United States, and in the coun- 
tries adjacent to the Slave Lake and Coppermine River, that we must 
expect exact determinations of this interesting curve No. 2. Un- 
questionably, 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 annu- 
ally under the direction of the Hudson’s Bay company, we may con- 
fidently 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 some person, properly qualified by previous prac- 
tise, to observe with the precision necessary on so particular occa- 
sion. : 
In regard to the great space in the northern hemisphere occupied 
by the Pacific Ocean, the numerous islands with which it is inter- 
Spersed, present points of observation of easier access than many 
parts of the respective continents. A commencement has already 
been made by Captain Liitke, commanding one of the Russian ships 
