The Tides. 207 



THE TIDES. 



By John Nader, Civil Engineer. 



The ocean tide, this mysterious breathing of the sea, has at- 

 tracted the attention of man from the earliest ages, and the cause 

 was often assigned to some mysterious, if not supernatural agency. 

 Pliny, in the first century, must have been studying the phe- 

 nomena before he exclaimed, " Causa in Sole Lunaque;" as we 

 proceed in this investimation we will see how nearly correct Pliny 

 was in his remark. Since the announcement of the Copernican^ 

 system of the universe, many theories have been advanced, all 

 parportiog to account for the tides. Some of these were very in- 

 genious and plausible, while others, as we will subsequently see, 

 bordered on the absurd. "Descartes,"'^ as Gruillemin says, " first 

 dared to draw the veil and sound the mystery, and if he failed, it 

 was only because of his preconceived ideas of the solar system." 



As we shall endeavor to deduce the cause from the efi:tc% we 

 will first investigate the various phases and features of the phe- 

 nomenon as they actually occur, and then endeavor to assign the 

 cause. Considerable observation and study are required to obtain 

 a clear understanding of the varied features of the tide, of the 

 disturbing influences arising from various sources, and of the 

 form of the true and distorted waves. 



The first feature observed, is the periodic rising and falling of 

 the surface of the ocean and the movement of the consequent 

 currents. 



The tidal wave in its simplest form is a lorig undulation of the 

 surface of the ocean, the length of which is the distance between 

 two consecutive high or low waters ; the vertical range is very 

 small when compared with the length, but increases as the length 

 diminishes ; the time, however, is and remains the same except- 

 ing in special cases. 



' Nicolaus Copernicus. Born Feb. 9, 1473, Prussia. Died May 24, 1543. 

 System de Mundi, 1507-1580-1548. 

 ^Descartes. Born, 1596; died, 1650; 54 years. 



