408 On the Formation of Bottom Ice. 



greater depth. However this may be, it is pretty certain that 

 the frost cannot penetrate, or ice masses form, at a greater 

 depth than eight feet in the sea. On the fishing lines no ice 

 is formed at a greater depth than fonr feet, and this ice is not 

 branchy, because the line is kept in even motion, but smooth 

 and tapering like an icicle. 



The plates of ice do not come up flat, but suddenly shoot 

 up edgewise, often with such force that they rise three or four 

 inches above the surface of the water, and often several are 

 piled one above the other. They are often broken in pieces 

 by their own weight, and it is only with the greatest care that 

 they can be taken up whole. Their colour is bluish like com- 

 mon ice. The stronger the frost is, the larger and more nume- 

 rous are these plates of ice. If it happens that one of these 

 ice plates lies by itself, and the weather is very still and cold, 

 its circumference quickly increases, and in a few hours it may 

 reach a size of two feet or more in diameter. A similar ice 

 formation, below the water, takes place throughout the whole 

 Cattegat, and we see such plates of ice floating all over the 

 sea, between Keellen and Jutland, at the same time, and in the 

 same manner. When the fishermen observe them they 

 directly make for land, for they often come in such quantities 

 they would soon encircle the boats and block up the passage. 



We will now, for shortness, ask the following questions, 

 and answer them thus : — 



In what manner does the freezing begin ? 

 Principally through small plates of ice which come up from 

 below, and after that freeze together. 



What is the size and colour of these plates ? 

 The size varies from one to about five inches in diameter, 

 and not one two lines in thickness. The stronger the frost is, 

 the larger are these plates. The colour is the same as com- 

 mon ice. 



Do they gradually become lighter and freeze together into 

 a covering of ice ? 



These ice plates become packed by the wind and stream, 

 and at first freeze into round lumps of different sizes, which 

 afterwards freeze together into a covering of fast ice. 



Is there any resemblance between these lumps of ice 

 before they are frozen tegether and a mass of dead sea 

 blubber (Medusce), which we often see driven up into a bay on 

 the coast after a storm in the summer. 



When these plates of ice first come up, they bear no re- 

 semblance to sea-blubber ; they are then too flat and thin ; but 

 afterwards, when they become worked and frozen together 

 into circular lumps, they very much resemble floating lumps of 

 Medusae. 



