Address of Sir Wm. Thomson at the Glasgow Meeting. 358 
been put forward seriously except in ignorance of elementary 
dynamical principles, to account for a change in the earth’s 
axis; we need no violent convulsion producing a sudden distor- 
tion on a great scale with change of the axis of maximum 
moment of imertia followed by gigantic deluges; and we may 
not merely admit, but assert as highly probable, that the axis 
present geographical position, and may have gradually shifted 
apparent acceleration; and how Delauney in 1866 verified 
ams’s result, and suggested that the explanation may be a 
retardation of the earth’s rotation by tidal friction. The conclu- 
. 
sion is that since March 19, 721 B. C., a day on which an eclipse 
