THE TIDES. 93 



to the general circulation and mingling of the waters in the ocean. 

 The influence which the ebb and flow of the tides exercise indirectly 

 on the commerce and civilization of nations is immense ; it is to 

 these movements of the sea that England owes in great part her 

 power and glory. 



In all times the people dwelling on the borders of the ocean 

 have understood, without being able to account for it, that the 

 alternate phenomena of ebb and flow depend on the position of the 

 moon and sun relatively to the earth. The coincidences that they 

 saw renewed each day between the movements of the tides, and those 

 of the large heavenly bodies, could not leave them in any doubt 

 of this. Sailors and fishermen, accustomed to look to the sky for 

 the signs of the weather, and indications of the route which they 

 ought to follow, had no trouble in ascertaining that the return 

 of every second tide corresponds exactly to the passage of the 

 moon over the same degree of the heavens ; that is to say, to the 

 commencement of a new lunar day. Following the phases of the 

 moon, at new, half-moon, or full, they saw the tides change in a 

 regular manner, and become successively higher and higher, and 

 afterwards, from day to day, lower, till the end of the lunar month. 

 Finally, the movements of the sun also announced to them before- 

 hand the approaching state of the waves, for the equinoxes of 

 March and September are always accompanied by very high tides. 

 These coincidences between the phenomena of the sea and the move- 

 ments of the moon and sun are so striking, that all barbarous 

 maritime tribes have remarked them, and have rudely symbol- 

 ized the idea in their songs. Thus the Scandinavian sagas re- 

 present Thor, the god of winds, blowing the water with a horn 

 which he plunges into the depths of the ocean, and by his power- 

 ful breath causing the waves to rise and fall by turns. What can 

 this strange legend signify, if not that the regular oscillations of 

 the tide depend on the cosmical forces to which the planet itself is 

 subject ? 



Nevertheless, these symbolic tales of the ancient Scandinavians 

 are far removed from that scientific theory of the tides, which the 

 researches and sagacity of I^ewton and Laplace have established. 

 Even Pliny, when he affirmed clearly that the tides are due '* to the 

 combined influences of the sun and moon," restricted himself to sum- 

 ming up in precise terms what all the dwellers on the sliores of the 

 ocean knew ; but he could not explain in what manner this influence 

 was exercised. The explanation of the mysterious phenomena of the 



