Temperature of Sea Affected by Diminished Transparency. 7 



field was upwards of three leagues broad, and its limit in a 

 northern direction could not be seen. The second, likewise 

 very extensive, had an immense iceberg in its centre. 



On the 30th March 1818, a sloop of war, The Fly, passed 

 between two large islands of floating ice in 42 degrees of 

 north latitude. 



On 2d April 1818, Lieutenant Parry met with icebergs in 

 42' 20' of north latitude. 



This year (1845) the English vessel Bochefort continued 

 enclosed, at the end of April and beginning of May, for 

 twenty-one consecutive days, in a mass of floating ice, which 

 ran along the bank of Newfoundland, advancing to the south. 



The sea is much less easily heated than the land, and 

 that, in a great measure, because the water is diaphanous. 

 Every thing, therefore, w^hich causes this diaphaneity to vary 

 considerably, will produce sensible changes in the tempera- 

 ture of the sea, immediately after in the temperature of the 

 oceanic atmosphere, and, somewhat later, in the temperature 

 of the continental atmosphere. Do causes exist, indepen- 

 dently of what science discovers to us, which may interfere 

 with the transparency of the sea to a great extent ? Let 

 the following be my answer : — 



Mr Scoresby has shewn, that, in northern regions, the 

 sea sometimes assumes a very decided olive-green colour; 

 that this tint is owing to medusae and other minute animal- 

 culse ; and that wherever the green colour prevails the water 

 possesses very little diaphaneity. 



Mr Scoresby occasionally met with green bands, which 

 were from two to three degrees of latitude (60 to 80 leagues) 

 in length, and from 10 to 15 leagues broad. The currents 

 convey these bands from one region to another. We must 

 suppose that these do not always exist ; for Captain Phipps, 

 in the account of his voyage to Spitzbergen, makes no men- 

 tion of them. 



As I have just stated, the green and opaque portions of 

 the sea must become heated in a manner difi'erent from the 

 diaphanous parts. This is a cause of variation in the tem- 



