EFFECTS OF SUCH A COLLISION. 



would be cast into the adjacent plains or valleys. It is evident 

 that a general destruction of the organised world would bo 

 inevitable. 



But eve<a though the change of axis and the change of velocity 

 of rotation of the earth might be so very inconsiderable, owing 

 to the smallness of the mass of the striking comet and other 

 causes, that such devastation might not take place, other effects 

 would ensue which would speedily show the disturbance con- 

 sequent on such a catastrophe. The least change in the axis 

 would cause a corresponding change in the position of the terres- 

 trial poles and the equator. The latitudes and longitudes of all 

 places on the earth would suffer a change, the extent of which 

 would be commensurate to the change of position of the axis of 

 rotation. 



But it is demonstrated in mechanics that a spheroid, such as the 

 earth is known to be, cannot permanently revolve round any axis 

 except its shortest diameter, that is the diameter which passes 

 through the two points which form the centres of its flatness ; and 

 such we know by exact and numerous observations to be the axis 

 upon which the earth actually revolves. Now, if by the collision of 

 a solid comet the earth were made to revolve on any other diameter, 

 it could not continue so to revolve. It would change its axis from 

 hour to hour until at length it would again revolve round its 

 shortest diameter. 



But during this continual change of axis, what inconceivable 

 physical and geographical confusion would arise ! Not only would 

 the latitudes and longitudes of places be constantly changed, but 

 their climates and seasons, the conditions and qualities of their 

 vegetable productions would undergo corresponding variations. 

 Animals would migrate from country to country, seeking a con- 

 genial climate, and flying from vicissitudes and extremes of 

 temperature which their instincts would not fail to tell them are 

 incompatible with their well-being. The distribution of land and 

 water, though perhaps exempt from the devastating effects attend- 

 ing extreme changes of velocity and direction, would nevertheless 

 gradually undergo a total and general change, and the geogra- 

 phical features of the earth, the land-marks of nations and races, 

 would be utterly deranged and effaced. 



To answer the question, then, whether the earth has ever at any 

 epoch been struck by the solid nucleus of a comet, we have only to 

 examine whether there be any traditions in history, or any physical 

 traces on the surface of the globe, of phenomena such as we have 

 described above. 



It is scarely necessary to observe that, in the records of history 

 and the traditions of nations, there are no traces of any such 



S3 



