ADDENDA. 
639 
It is hoped that Prof. Hackley, of Columbia College, New-York, and Lieut, Roberts, of 
the IT. S. Military Academy at West-Point, will enter into a mathematical investigation of 
the influence of a diminished diameter of the earth upon the length of our day, considering its 
spheroidal form, variable density, etc.; and whether the influence of the planets in varying 
the length of the day, infinitesimal as it is, acts as a compensation for the effects of refrigera¬ 
tion, and the removal of materials from higher to lower levels by alluvial action. 
