208 Mr. A. Tylor on Tides and Waves. 



If fig. 4, PI. IV., is correct, there can be no great heaping up 

 of water or any tidal wave generated in one direction, as has 

 been sometimes assumed ; for I show that the action of the tide 

 is a reciprocating action, and has as much motion from west to 

 east as from east to west. 



The assumption of a great heap of water travelling in one 

 direction, or producing a certain amount of retardation of 

 the rotary movement of the earth, quite unbalanced by ac- 

 celeration, has been taken as a serious fact ; many writers 

 of reputation have supposed that the rotation of the. earth 

 must be affected by this hypothetical wave-action in one di- 

 rection. 



My view of the general theory of the tides (fig. 4, PI. IV.) 

 differs materially from those generally accepted ; and I cannot 

 understand the existence of an intumescence (shown in figs. 1, 

 2, and 3, PL IV.) under the moon at all if the subject is treated 

 in the ordinary manner of reasoning. 



I entirely disbelieve in tidal action having the smallest effect 

 on the rotation of the earth. It is a balanced action. The sun 

 might produce currents by unequally heating water, which 

 might affect the surface-level of the sea and cause inequalities ; 

 but of this there is no positive evidence. I show by fig. 3, PI. III. 

 that, under certain circumstances observed, a current may travel 

 against the slope of the surface. This I noticed in your Journal 

 in 1853. The existence of a current is of itself, therefore, no 

 proof of what is the direction of the slope of the surface. I find 

 that an elevation of level of 2 inches on the east maintained over 

 the west side of the Atlantic, or vice versa, where water is very 

 deep, would generate a current of 3 feet per minute in the ocean 

 in the direction of the slope, supposing the Gulf-stream did 

 not intervene and there was no tidal action. The western water 

 would take 5 years to cross the Atlantic at a speed of 3 feet 

 per minute, to reestablish equilibrium. If the difference of level 

 were produced by luni-solar action, it would cause no current 

 until the force creating it was withdrawn. 



If 58 miles per hour is the greatest velocity a surface-wave 

 could travel at in the deepest part of the Atlantic, such an in- 

 tumescence, even if maintained, would have only proceeded 348 

 miles before the moon's influence would be exerted against its 

 motion. The great earthquake-impulse of Lisbon in 1755, pro- 

 ceeding through deep water, did not travel to Barbadoes faster 

 than 6 miles per minute; and an intumescence of equal force or 

 impulse created on the W. coast of America, in the latitude of 

 Brest, would meet contrary luni-solar attractions when half- 

 way across the Atlantic. No intumescence could be raised in 

 deep water without forming a gap below. 



