Mr Scoresby m the Cdkmr of the Greenland Sea^ 11 
iiorth-east and south-west; but of very variable dimensions: some- 
times, I have seen it extend two or three degrees of latitude in 
length, and from a few miles, to ten or fifteen leagues in breadth. 
It occurs very commonly about the meridian of London, in 
high latitudes. In the year 1817, the sea was found to be of a 
blue colour, and transparent, all the way from 12° east, in the 
parallel of 74° or 75°, to the longitude of 0° 12' east, in the 
same parallel. It then became green, and less transparent. 
The colour was nearly grass-green^ with a shade of black. 
Sometimes the transition between the green and blue water is 
progressive, passing through the intermediate shades in the space 
of three or four leagues ; at others, it is so sudden, that the line 
of separation is seen hke the rippling of a current; and the 
two qualities of the water keep apparently as distinct as the wa- 
ters of a large muddy river, on first entering the sea. In 1817, 
I fell in with such narrow stripes of various coloured water, that 
we passed streams of pale green, olive green, and transparent 
blue, in the course of ten minutes sailing. 
The food of the whale occurs chiefly in the green coloured 
water ; it therefore affords whales in greater numbers than any 
other quality of the sea, and is constantly sought after by the 
fishers. Besides, whales are more easily taken in it, than in 
blue water, on ax:count of its great obscurity preventing the 
whales from seeing distinctly the approach of their enemies. 
Nothing particular being observed in this kind of water, 
sufficient to give it the remarkable colour it assumes, I at first 
imagined that this appearance was derived from the nature of 
the bottom of the sea. But on observing that the water w^as 
very imperfectly transparent, insomuch that tongues of ice, 
two or three fathoms under water, could scarcely be discerned, 
and were sometimes invisible, and that the ice floating in the 
olive-green sea was often marked about the edges with an 
orange-yellow stain, I was convinced that it must be occasioned 
by some yellow substance held in suspension by the water, cap- 
able of discolouring the ice, and of so combining with the natu- 
ral blue of the sea, as to produce the peculiar tinge observed. 
F or the purpose of ascertaining the nature of the colouring 
substance, and submitting it to a future analysis, I procured a 
quantity of snow from a piece of ice that had been washed by 
the sea, and was greatly discoloured by the deposition of some 
