Cn. XXn.] COLOUE OF TKE SEA. 389 



marked when, after squally weather, we were in a latitude 

 in which the soundings marked in the chart were 2350 

 fathoms, but the sea was of a Hght-green colour ; and the 

 remark I have entered in my journal was that for some two 

 or three days past, during windy weather, the sea has lost 

 its blue colour, and to-day seems washed out. This peculiar 

 phenomenon I attribute to the commotion which the sea 

 has undergone, haviag entangled air with the water ; and 

 although no masses of foam are anywhere visible, myriads 

 of minute air bubbles, mingled with the water, modify the 

 usual absorption, of light, and reflect more or less of the' 

 yellow rays. , That this is the proper explanation is con- 

 firmed by a fact I have more than oface noticed, viz. that 

 when, in fine weather, the sea has been of the ordinary 

 dark-blue colour, the wake of the ship has been marked by 

 a path of light-green water for a long distance behind. 



That blue is the natural colour of the water is moreover 

 proved by the fact, that whatever the colour of the sea under 

 the changing influences of light and shade, whether dull and 

 leaden, or bluish-green, the water in the screw-weU, — upon 

 which we look directly down, and which is liable to no 

 lateral reflection or disturbing influences such as the open 

 sea must of necessity be subject to from the angle at which 

 our eyes regard it, — ^is always blue, sometimes pale, some- 

 times dark ; but under the most favourable circumstances, 

 of an intensity which frequently attracts the admiration of 

 those to whom it is an every-day occurrence. I think it 

 was Sir Humphry Davy who attributed this blueness of the 

 sea to. the presence of iodine ; but I cannot help thinkirfg 

 that it is an inherent property in the water, just as some 

 shade of the same colour appears to be an inherent property 

 in the air of the atmosphere, that is to say, that sea-water. 



