OF GEOLOGICAL DYNAMICS. 91 



latitude, may be exerting, at the present time, an 

 accelerating influence of a sensible amount upon 

 the earth's rotational velocity, and rendering the 

 observed retardation less than that due to the tides. 

 For, as shown in my lecture on Geological Time 

 (12 and y\ppendix), the dynamical theory of the 

 tides, and known facts regarding the interval 

 between " full and change of the moon," and the 

 times of spring tides, render it difficult to see how 

 tidal retardation of the earth's rotation can be so 

 little as to make the integral of lost time in a cen- 

 tury amount to only tw r enty-two seconds. It is 

 conceivable that something of this accumulation of 

 ice suggested by Professor Huxley, or erosion of 

 matter from the equator suggested by Mr. Croll, 

 may, to a considerable extent, have temporarily 

 counteracted the tidal retardation. 



15. Now Professor Huxley asks, "If tidal re- 



" tardation can be thus checked and overthrown 



" by other 1 temporary conditions, what becomes 



of the confident assertion based upon the 



1 I presume the presence of the word "other" here is to be 

 regarded as an undetected "erratum." 





