And now what can we say of the colour of the sea? I used to think that it was always a clear green, but that was because the sea which I knew appeared to be that colour, for I had seen it only near the shore, where the bottom was fine white sand, and the sunset light made the water shine like an emerald. And so the sea was green to me, and I was often puzzled and vexed to find that I could never catch this beautiful green water; for you know that if you dip your bucket where the sea looks greenest or bluest, all the lovely colour will seem to be left behind, and your bucket-full will look as colourless as water drawn from a well. Where the sea is dark blue, you may be sure that it is deep where it looks gold and purple, the sun has tinged it with the glory of his rising and setting; where it is grey and sad, it takes its sorrowful hue from the rain-clouds overhead. These are some of the reasons why the sea is of such different colours, but the water is sometimes coloured, to some extent, by myriads of living things which give it a reddish tinge; in the cold Northern Ocean, where the icebergs are, travellers tell us the sea is green because there its tiny inhabitants are green; while those who have sailed in the South American waters tell of countless swarms of minute creatures which make them glow like fire on a dark night, lighting up the crest of every wave as it rolls past the ship. The sea is also coloured by those beautiful plants which we often call by one common name--seaweeds, but which are almost as varied in their way as the land plants are. Columbus, when sailing sadly through unknown seas in search of the New World of which he had dreamed so long, came upon water so covered with long green weeds that it seemed like a floating meadow, while his vessels could hardly make their way through the grassy tangles of what is now known as the Gulf-weed. I have seen the sea off the coast of Ireland green for miles, with long, ribbon-like plants covering its sandy bottom, sheltering, and perhaps helping to feed, the millions of crawling and running and swimming creatures, many of them so small as to be nearly invisible, which find their home there. This sea-grass, or Zostera, the only flowering plant to be found in the sea, is very useful to the poor people who live near the coast. They gather it when the tide is low, and dry it in the sun, and it serves them for nice soft beds; though I should think they must always keep a briny, fishy smell about them. [Illustration: "O'ER BANKS OF BRIGHT SEAWEED, THE EBB-TIDE LEAVES DRY."]