VI PREFACE-DEDICATION 



Indeed, my title is not so fantastic as one 

 might think. We have always heard of the 

 sea as " deep blue " and fancied perhaps it could 

 be no other color; yet if you look do^vn upon 

 it from a cliff where it flows over white rocks 

 you will find it a shade of green, and if you 

 plunge beneath the surface and open your eyes 

 under water you will discover it is still an- 

 other shade of green. Then there are great 

 arms of the ocean that from their color are 

 known as the Ked Sea, the Yellow Sea, the 

 White Sea, the Black Sea. It has many hues 

 in different quarters of the globe. But none 

 of these local colors is comparable in extent or 

 continuance to the color reflected from the sea's 

 surface. Whatever hue is in the sky, whatever 

 tint may be produced by heat or cold, by sun- 

 light or moonlight or cloud-light, the water 

 mirror will give it back. The sea is not blue 

 or green or yellow alone, but all the rainbow 

 hues blended and fused by sunlight into irides- 

 cent fire. Therefore why not the Opal Sea? 



And, again, I mean by that title to suggest 

 that this book, though it treats of scientific 

 things at times, is, in design at least, a book 

 of color and atmosphere. The splendor of the 

 sea rather than its origin, its cartography, or 

 its chemistry has been my aim. It may seem 



