246 THE POPULAR SCIENCE MONTHLY. 



THE COLORS OF WATER 



By CAEL VOGT. 



" f^\ RANDPA," asked my two grandchildren, as if with one 

 vZT voice, " shall we pass over the blue lake when we go to 

 Geneva ? " 



Our residence at Salvan, a charming village of the canton 

 Wallis, about a thousand metres above the level of the sea, was 

 nearing its end. The return journey was the subject of lively 

 conversation, and we were almost entirely occupied with the 

 fancies of the children, who asked no end of questions. "We 

 shall go across the blue lake," I said. "First we shall go 

 down to the station. Grandma and I will go in carriages, you 

 others will walk. Then we shall take the railway train and go 

 down to the lake. The steamboat will be there, and as soon as 

 we are aboard " 



"Grandpa," interposed the others, "why is the lake so 

 blue?" 



I was somewhat confused by these questions. If a fool can 

 ask more questions than ten men can answer, a child can perplex 

 more than a hundred grandpas. An evasive reply, like " It is 

 blue because it is not yellow like the Oder at home," was not 

 available with my children. It is an old observation that the 

 simpler a phenomenon of Nature appears at first sight, the more 

 complicated it is in fact ; but it is always well to recollect that 

 there is no simple phenomenon in Nature, that all that ever hap- 

 pens or is perceived by our senses is only a result of very differ- 

 ent or even opposing forces and causes, which we must not only 

 learn by observation, but must also separate from one another by 

 experiment, if we would come to a conclusion that has hands and 

 feet. Every one can see that the Lake of Geneva is blue, and 

 most persons regard the subject as quite simple and clear, with- 

 out probing further into the causes of the blue color. But 

 if a child in his naive candor asks for the reason of this color 

 which has struck him because the waters of his home are not 

 like it, there floats before the mind of the expert an unantici- 

 pated multitude of problems in optics involving the most difficult 

 laws and broad knowledge, and over which mathematicians and 

 physicists and students of every kind, artists and poets, have 

 racked their brains, without having ever reached a definite solu- 

 tion. How, then, shall he convey ideas to a child which shall 

 give an answer to the question adapted to his powers of compre- 

 hension ? 



I was thinking of preparing a small water-color drawing, when 



