1819.] Memoirs of the Wernerian Society, Vol. II. Part Il. 63 
eenish shade of colour, it is considered by the whalers as 
formed by the congelation of sea-water, and called salt water ice. 
When this ice is thawed, it sometimes yields fresh water, and 
sometimes brackish water. The specific gravity of this ice, 
according to Mr. Scoresby, is 0°873. 
The name fresh water ice is applied to ice which has a black 
appearance while floating in the sea, but a beautiful green hue 
and transparency when removed into the air. Its transparency 
is usually interrupted by numerous small, pear-shaped air-bubbles. 
When formed into convex lenses, it collects the sun’s rays into a 
focus, and sets fire to gunpowder, &c. precisely as a glass lens 
would do. Its specific gravity, according to Mr. Scoresby, is 
0937. 
It has been conceived by many, that the ice which covers the 
polar seas has its origin from the land; but Mr. Scoresby is of 
opinion that the vicinity of land is not necessary for the formation 
of ice. He has seen the sea freeze at a distance from land, both 
when smooth and when agitated by the wind; and he describes 
the appearances which take place in both cases. He conceives 
that, during the summer months, the polar ice splits, and one 
portion separates to a distance from the other. In winter, the 
interval between these two portions freezes, and becomes covered 
with snow. This snow is melted during the ensuing summer, 
and the pond of water, thus formed upon the ice, freezing the 
ensuing winter, constitutes a field of ice. 
Fields have a constant tendency to drift to the south-west. 
This occasions the destruction of many, whose place is supplied 
by others from the pole. Fields sometimes acquire a circular 
motion of three or four miles an hour. When two fields moving 
different ways meet, they act upon each other with prodigious 
energy, breaking each other in pieces, and piling up the frag- 
ments to a great height. When ships are interposed between 
two fields, in such a case, the consequence is alarming, and 
often destructive. 
The term iceberg is commonly applied to those immense bodies 
of ice situated on the land, fillmg the valleys between high 
mountains, and generally exhibiting a square perpendicular front 
towards them. They recede backwards inland to an extent 
never explored. Large pieces may be separated from these ice- 
bergs in the summer season. These masses, floating in the sea, 
still retain the name of zcebergs, ice islands, or ice mountains. In 
height, above the surface of the sea, they may be 100 feet, or 
more, and below the surface, 100 yards, or more; while their 
diameter varies from a few yards to some miles. They abound 
in Davis’s Strait ; but are few in number and small in size off 
the coast of Spitzbergen. On that account, Mr. Scoresby thinks 
that they rather originate in sheltered bays of the land than from 
land icebergs. They occur also at some hundred miles’ distance 
from land towards the north. The perpetual accumulation of 
