Mr Scoresby on the Seven Icebergs of SpUzbergen, 
which they consist is, indeed, a little porous ; but considerable 
pieces are found of^ perfect transparency. Being wholly produ- 
ced from rain or snow, the water is necessarily potable. Icebergs 
have also the same kind of origin as glaciers. The time of their 
foundation, or first stratum being frozen, is probably nearly co- 
eval with the land on which they are lodged. Their subse- 
quent increase seems to have been produced by the congelation 
of the sleet of summer or autumn, and of the bed of snow an- 
nually accumulated in winter, which, being partly dissolved by 
the summer sun, becomes consolidated ; and, on the decline of 
the summer heat, frozen into a new stratum of transparent ice. 
Snow subjected by a gentle heat to a thawing process, is first 
converted into large grains of ice, and these are united, and 
afterwards consolidated, under particular circumstances, by the 
water which filters through among them. If, when this im- 
perfectly congealed mass has got cooled down below the freez- 
ing temperature by an interval of cold weather, the sun break 
out and operate on the other surface so as to dissolve it, the 
water which results runs into the porous mass, progressively fills 
the cavities, and being then exposed to an internal temperature 
sufficiently low, freezes the whole into a solid body. Or if, 
when the ice has been cooled by a low temperature, a fog or 
sleet occur, it is frozen as it falls, and encrusts the body of the 
iceberg with an additional varnish of ice. 
Icebergs are as permanent as the rocks on which they rest ; 
for though large portions may be frequently separated from the 
lower edge, or, by large avalanches from the mountain summit, 
be hurled into the sea, yet the annual growth replenishes the 
loss, and, probably, on the whole, produces a perpetual in- 
crease. But the annual supply of ice is not onlv added to the 
upper part, but also to the precipitous crest facing the sea ; 
which addition being run into, or suspended over the ocean, 
admits of new fragments being detached, and of the renewal 
of the vitreous surface which it presents to the eye after each 
separation. In some places, indeed, where the sea is almost 
perpetually covered with ice, the berg or glacier makes its wdy 
to a great extent into the sea, until it reaches the depth in the 
water, of several hundreds of feet ; and then being capable of 
large dismeniberments, gives rise to the kind of mountainous 
