260 THE MEDITERRANEAN SEA. 



the Cyclone or circular hurricane, which sweeps over the 

 ocean, a calm girt round by a whirlwind. Even earthquakes, 

 in some of their phenomena of propagation and vibration, 

 come under the same analogy; strange though it may 

 seem that the solid crust of the globe should in any way be 

 submitted to that law of interference of waves of horizontal 

 vibration, which produce a rotatory movement in the case of 

 the circular polarisation of light. Imagination, pressing yet 

 beyond, and looking especially to the composite nature of the 

 motion in all these cases, might extend the relation even to 

 the great movements of the solar system ; or still more 

 remotely in space to the spiral forms of nebulae which Lord 

 Rosse's telescope has disclosed to us. But putting aside these 

 more hypothetical analogies, we have sufficient reason to 

 associate together, under some cause or principle of motion 

 not yet wholly understood, the simpler terrestrial phenomena 

 to which we have just alluded ; and many others which come, 

 though less explicitly, under the same law of action. And 

 this is one of the many physical questions still open to 

 research, and inviting both observation and experiment in aid 

 of the solution which it is sure in the end to obtain. 



We have lingered so long on the physical history of the 

 Mediterranean, that little room is left for comment on that 

 other part of its history, of which men- and nations form the 

 subject and the interest; a subject indeed so vast, and an 

 interest so various, that it would be futile to attempt more 

 than a mere outline of what can only be compassed in a 

 complete work. But the topic is closely blended with, and 

 illustrated by the physical history of this Sea; and much 

 may be gained to the clearness and concentration of human, 

 history in its most important epochs, by grouping its events 

 in their relations to these remarkable shores. In each suc- 

 cessive age, from the earliest date and record to which we 



