292 distract of a Memoir on the Limits 



geroe (the island vvhere Cape North is) we see no traces above 

 130 metres : the snow limit will therefore be S05 metres = 227 

 + 578 at Hammer Fest, and 70S metres = 578+ ISO at Cape 

 North. Tlie rocks of this last point are only 390 metres high, so 

 that it wcinld require 318 metres more in order that the snow 

 should not melt in summer. 



One remark of great truth we owe to M. de Buch, namely, 

 that the snow limit ought to depend chiefly on the temperature 

 of the months during which the snows usually melt ; so that it is 

 not the mean temperature which determines its height. Thus in 

 the interior of the Gulf of Altcn, the mean degree of the thermo- 

 meter is less than at Cape North*, and yet the snow limit there 

 is much higher. This is because one and the same mean annual 

 temperature may result from very different moiithly mean tem- 

 peratures; as we may be convinced by the subjoined table, which 

 presents, month by month, the mean temperatures of Mageroc 

 (an island of Cape North), and of Uleoborg, under the parallel of 

 Torneo. 



65". 



We see that the definitive mean temperatures of the year differ 

 little from each other in these two places, and yet the mean of the 

 positive temperature rises at Uleoborg to 10", whereas it does 

 not go beyond 4 ' at North Cape. Those considerations add to 

 the interest which ought to be excited for the determination of 

 the snow limit : — if its height in fact is only regulated, as we have 

 said before, by the summer temperature, it will become in some 



* The mercury often freezes in the open air at Alten, but never at Cape 

 North. Tlie thermometer falls every winter at Altcn to 25° below zero. At 

 Cape North it is only —12', or at most — 15", and —17 05 is the extreme 

 point. Thus the sea never freezes in those regions. We must be 20 or 80 

 sea lea<;ues from the latter promontory betore we see the islands of ice, and 

 itill they are very far off in the horizon.— Jl/. dc Buck. 



respect* 



