Observations in Siberia, 11 



those localities of peculiar interest, which it might be expedient 

 to visit for more particular enquiry. A single expedition might 

 accomplish all this, without extending the duration of the 

 voyage to an undue length, or interfering with other important 

 objects of scientific research : and we may assuredly affirm, that 

 were this service the single purpose, and sole object accom- 

 plished, by a scientific expedition, it would of itself confer no 

 ordinary distinction. 



In what has hitherto been said, observations made on land 

 have alone been taken into account : the motion of a ship, and 

 the quantity of iron necessarily employed in her equipment, 

 impeding the prosecution of such researches at sea, and pre- 

 senting embarrassments which, to say the least of them, are 

 very difficult to surmount, and but too likely to impair the 

 accuracy of the results. Still, when we consider how large & 

 portion of the southern hemisphere is covered by the ocean, it 

 does appear desirable to make the endeavour to obtain the best 

 results, that circumstances will permit, over such extensive por- 

 tions of the globe ; and particularly as in the opinion of those, 

 who from experience are most competent to judge, it is possible, 

 by great care, to obtain results worthy of confidence. M. Hum- 

 boldt has recorded several observations which he made himself 

 at sea, in the northern Atlantic, both of the Dip and of the 

 Intensity, the latter of which accord well with the curves of 

 intensity traced in the accompanying sketch. M. Hansteen 

 believes, that by giving a dipping needle the sort of suspension 

 used in Captain Cook's third voyage, — by choosing those times 

 for observation when a calm sea and moderate wind allow the 

 ship to keep a steady course, — by confining the use of the in- 

 strument always to the same place on the ship's deck, — and by 

 comparing the results on board and on shore on all occasions, 

 when in harbour, — observations on board ship might become 

 very valuable. I will venture to add an extract on this subject 

 from Captain Lutke's letter, whose remarks are the more en- 

 couraging as, when he quitted Europe, he was by no means 

 sanguine of success in the use of delicate magnetic instruments 

 at sea. " Je dois pourtant faire quelques remarques sur les 

 observations faites a bord. J'avais ete, comme vous, en doute 

 qu'elles puissent donner des resultats dignes de confiance, mais 



