made during the recent Northern Expedition. 345 
same hour of the day ; and it is remarkable that the position 
of this line, as referred to the true meridian, has precisely the 
same bearing as in England ; viz. that is about N. 40° west. 
Besides these daily changes in the direction of the horizontal 
needle, it was found that its intensity also experienced a very 
considerable change ; and observations were accordingly insti- 
tuted relative to that inquiry, and continued hourly for several 
months. These were performed by registering the time which 
the needle required to perform a certain number of vibrations ; 
and which time varied from 17 to 18 minutes, increasing and 
decreasing regularly twice in the day with the variation. A 
similar change is known to obtain in Europe ; but it is very in- 
considerable. It appears, therefore, that both the daily varia- 
tion in direction and in intensity, are dependent on the same 
cause ; and that this cause, whatever it may be, operates much 
more powerfully in places where the dip is great, than in others 
where it is less considerable, as in England, France, &c. 
We understand that Lieutenant Foster has still another 
communication to lay before the Royal Society, which is intend- 
ed to point towards the cause of these various changes; and 
which is founded on a comparison of simultaneous observations 
on the intensity of the dipping and horizontal needle ; but we 
are unacquainted with the results and deductions of this ingeni- 
ous and accurate observer on this particular subject. The in- 
quiry is one of great interest ; and we are glad it has fallen into 
such able hands. If the cause in this case can be satisfactorily 
traced, we feel assured that terrestrial magnetism will soon be 
placed upon a level with most of the other physico-mathemati- 
cal sciences. Should this be the case, although no other result 
had been obtained by the recent expedition, we should consider 
that a full reward had been secured for all the labours and ex- 
pences attending this otherwise unfortunate voyage. 
In concluding this brief notice, it is but justice to state, that 
the communications referred to above, although delivered only 
in the names of Captain Parry and Lieutenant Foster, may be 
almost considered as the joint labours of all the officers of the- 
expedition. When we consider that the operations were carried 
on at a considerable distance from the ship, in a temperature 
frequently 40° and 47° below zero, with the sun for a considera- 
