1848.] 



LUBBOCK ON CHANGE OF CLIMATE. 



surface remains unchanged ; no change of climate can obtain except 

 from a change in the internal temperature, or in the sun, the source 

 of heat. 



But a change in climate alone is not sufficient to account for geo- 

 logical changes, which indicate that water now covers land formerly 

 dry, and vice versa. 



The preceding conclusions are not modified by the attraction of 

 the moon, or by those causes which produce the precession of the 

 equinoxes, so that at Greenwich for example the latitude remains, as 

 Mr. Airy informs me, absolutely unchanged within those limits of 

 which the errors of the observations are susceptible. If however we go 

 back to the origin, it is unUkely that when the earth was first set 

 spinning, the axis of rotation should exactly coincide with the axis of 

 figure, unless indeed it were all perfectly fluid. We may however 

 go back to some time less remote, and suppose the axis of rotation 

 not coinciding with the axis of figure, and the earth in a semi-fluid 

 state, or rather, in consequence of tlie different degrees of fusibility 

 of diff'erent substances, partly solid in irregular masses and partly 

 fluid. We then advance to another period more recent in which 

 the earth consisted of land and water, and was suited for the support 

 of animal life. We may if we please consider this as the original 

 state. The only hypothesis I wish to insist upon as essential is, that 

 the axis of rotation had not the same geographical position as at 

 present. 



In order to take the simplest case of the effect which a displace- 

 ment of the axis supposed possible may have had upon the relative 

 positions of land and water, suppose the solid part of the earth to 

 consist of a spheroidal nucleus revolving about the axis CP. The 

 effect of this would be to throw the 

 water into the position IKML about 

 the equator, the greater or less pro- 

 tuberance being caused by the greater 

 or less velocity of angular rotation. ^' 

 It is evident that if the body after 

 any length of time moved about any 

 other axis of rotation, the water 

 would occupy a position about the new equator, land would become 

 sea and sea land, &c. &c. 



Now suppose a point situated at D with latitude QCD, revolving 

 about the axis CP and submerged, were after a lapse 

 of time to revolve about an axis CP' and having 

 latitude DCQ', it would cease to be submerged, but 

 at the same time would be in a colder climate, which 

 is consistent with what you find takes place in 

 Europe (vol. i. p. 155) ; but if we consider what 

 takes place at the point D' situated at a distance 

 of 1 80° longitude from D, we find precisely the reverse : primitively 

 dry the point D will become covered by sea, and will acquire a hotter 

 climate. The countries differing in longitude from us by 180° are at 

 present submerged by the Pacific. 



