OCEANOGRAPHY. 417 



The foregoing considerations enable us to appreciate in its principal 

 characteristics the method employed in oceanography. The applica- 

 tion of experiment and of measurement seems at first particularly diffi- 

 cult, if not impossible. It is neither. As regards the ocean, it is cer- 

 tain that the phenomena apparent there are more than complicated — 

 they are terrible; and their grandeur apparently puts them far beyond 

 the power of man. It would be of no use to approach the study 

 directly. However, even the forces of the sea are forced to yield to 

 experimentation on condition that we proceed gradually, studying first 

 lakes — oceans in miniature, governed by laws similar, although less 

 complicated, and consequently more easy to discover and verify. In 

 oceanography a phenomenon must pass through three phases of study : 

 It is established on the ocean, found in lesser degree on lakes, and 

 studied by synthesis in the laboratory. Thus its law is discovered. 

 Then, taking the inverse order, it is ascertained whether the law 

 is verified on lakes, and at last we come back to the ocean. We 

 observe whether the law holds good there, and in case of modifications 

 (which usually occur) we seek their causes and consider what new ele- 

 ments have become involved which were absent, or perchance inef- 

 fective, on lakes or in the laboratory. The study is now complete and 

 definite, since, if necessary, we may return to the laboratory, where, rich 

 in the suggestions which have arisen from our new survey, fortified by 

 a first approximation, we can arrive at a greater precision, thanks to 

 a new synthesis established by new experiments. We work from the 

 known to the unknown and from the simple to the complex, retracing 

 our steps if necessary. 



The objection has been made to the experimental method that phe- 

 nomena in miniature such as we can produce in the laboratory are not 

 identical with natural phenomena, since they represent them on a 

 reduced scale. This reasoning rests on a misunderstanding; every- 

 thing goes to prove the contrary. Why should a heavy body left 

 unsupported descend into the sea in any different manner than it 

 descends in a tube some meters in height filled with salt water? If 

 the changes are brought about by the duration of the fall, the depth, 

 the pressure of the layers of water, and other circumstances, these 

 changes can be studied and estimated by means of separate experi- 

 ments. It is the usual method of resolving a natural phenomenon by 

 means of curves of a single equation with multiple variables. Admit- 

 ting that in certain cases a single experiment in the laboratory is 

 insufficient to reproduce the phenomenon, yet a series of experiments, 

 each of which would be performed to make clear the action of one of the 

 components of the problem, would represent it in its entirety. When, 

 for example, we have measured iu a tube 3 or 4 meters long the dura- 

 tion of the fall of globigerina in sea water, we evidently do not learn 

 all the laws of such a fall in the sea. It would be otherwise if, after 

 having made the experiment with ordinary pressure, we repeat it with 

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