Haughton — On the Effects of Lunar and Solar Tides, 8fc. 609 

 but T= 86,400 seconds = sidereal day ; 



w = 20 X 60 X 6000 = 7,200,000 feet ; 

 a = 21,000,000. 

 Substituting these values, we finally obtain 



8T= + 3,561,000 co'w. {F ter.) 



The range of tide for an equatorial canal, with moon in equator, is 



c-a = ^-, 

 lira 



where 8 is the depth of the canal. 

 Hence, we have 



c-a k^ 



Substituting the proper values, we find for the equatorial canal, 10 

 miles in depth, 



c - a = l'2lb feet, 

 1 



16,500,000 



Substituting this value in {F ter.) we find 



76,130,000 • ^ ^ 



It would therefore take upwards ofl& million years for the residual 

 tidal current produced hy the moon, in the ocean collected into an equatorial 

 canal, to increase the length of the day ly one second. 



Corollary. — As the tidal effect of the sun is one-half the tidal effect 

 of the moon, the residual current produced by both would take up- 

 wards of 50 million years to lengthen the day by one second. 



