TIDAL EVOLUTION 



BY B. R. BAUHQARDT. 



All phenomena may be grouped into two classes those 

 that are rythmic or periodic in their nature, and those that 

 are constant and unchanging, that is, do not increase and then 

 decrease with a regular rythmic periodicity. 



To the first class, which is by far the largest, belong all 

 the more obvious phenomena connected with the various man- 

 ifestations of force in nature, such as light, heat, electricity, 

 sound, motion, etc., as well as those more mysterious ones 

 which we comprehend under the general term of life. 



The swaying motion of a reed in a stream, the rustling 

 of the leaves in a tree, the pulsation of the blood in the 

 arteries and veins of the human body, the rise and fall every 

 twelve hours of the tides on our seashores, the periodic 

 maxima and minima every eleven years of spots on our pri- 

 mary, the sun, the accelerating and retarding motions of the 

 planets in their celestial orbits, the inequalities of our satellite, 

 the precession of the equinoxes that wonderful wabbling 

 motion of our earth's axis around the celestial pole in a 

 majestic orbit requiring 25,000 years for its accomplishment 

 the occillating change of position of the major axis of the 

 earth's elliptical orbit the great cycle of the solar system, 

 when, according to L,a Grange, all the planetary perturbations 

 shall have compensated each other and a new cycle commenced, 

 the wonderful periodic increase and decrease of light in 

 many of the variable stars and many other astronomical phe- 

 nomena are all, I think, typical illustrations of the first class, 

 or those that are decidedly rythmic in their nature. 



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