A. Anderso)i — On Changes of Climate. 353 



the bounds of the Polar Circle. To subsequent deflections of the axis 

 various observed phenomena may consistently be ascribed ; and it is 

 as a sequence to the latest convulsion, and pending the resulting dis- 

 turbance, that the enormous evaporation and condensation of the 

 Glacial Period may be conceived to have proceeded.' I do not pro- 

 fess to enter upon the physical minutige of this stupendous process ; 

 leaving that to the imagination in view of obvious natural laws. 

 Immediatelj' antecedent, however, to this latest convulsion, I assume 

 to have existed the class of extinct Mammalia typified by the woolly 

 Elephant and Ehinoceros of the north, and the ancient Hippopota- 

 mus of what are now the temperate zones : ^ by this convulsion I 

 infer they were destroyed. 



The grounds for this inference, as I shall endeavour to show, do 

 not exist entirely in the imagination. The condition of the two well- 

 authenticated specimens of the first-named animals revealed to view 



1 The disturbance here alluded to may be subject to the following explana- 

 tion. Under an established law of Mechanics the sudden change of the balance 

 of gravitation supposed must necessarily have been attended with a corresponding 

 nutation in the vertical plane, comparatively like the oscillation of a pendulum, or 

 the vibrations of the magnetic needle when accidentally deflected. The first effect 

 hence arising would have been to produce an abnormal declination ; in other words, to 

 extend temporarily the limits of the polar zones far beyond their pei-manent confines : 

 the converse effect, uponreaction, to contract them for a time proportionably, though 

 to a less extent. Hence two extremes of climate, both abnormal, must be conceived 

 to have resulted during an indefinite interval. Successive alternations, each gradually 

 decreasing in intensity, would have followed, until the globe at length subsided under 

 the gravitating force into that state of permanency which it has since retained. The 

 imagination is lost while contemplating either the extent or the duration of the 

 mechanical process thus theoretically assumed. From the vast inertia, however, of the 

 disturbed mass suspended in space and subject to no retarding infiuence beyond that of 

 gravitating attraction, it seems obvious that the effect must have been both great and 

 long continued : and specially that the extremes of climate, occurring at the reverting 

 points, must have been greatly protracted. This view admitted, it follows that the 

 condensation of the vapours arising from the cooling oceans must have been immeasur- 

 ably great. A condition of the globe may be conceived of under which, shrouded in 

 mist impenetrable by the solar rays, the formation of snow must incessantly have pro- 

 ceeded. On the contrary, at the opposite point, under a temperature alike extreme, 

 vast floods must have resulted from the melting snows : again succeeded by a reversed 

 condition, producing ice. Thus alternately the process would have continued, each 

 successive revolution lessening in degree, until ultimately the shaken sphere subsided 

 into that normal condition of repose which it has since retained. 



The floods thus generated upon the polar confines, in tbeir progress towards the 

 equatorial regions would not. it may be inferred, have assumed a course continuing 

 due south, but deflecting gradually to the westward, in obedience to the same physical 

 law by which the course of the trade-winds is regulated ; a result, at least with regard 

 to the Northern Hemisphere, in accordance, I believe, with the course of the ice-diift 

 observed both in Europe and America in those positions where local obstacles have 

 not casually diverted it. By the agency of these floods, in addition to the ice-con- 

 tained fragments of rocks with the remains of extinct races of animals, the timber, 

 leaves, and other vegetable matter, the produce apparently of the far north in the 

 antecedent condition of the globe, have likewise been transported. These, as shown 

 by the observations of Mr. Charles Whittlesey, are discovered in America imbedded 

 deeply in the diluvial drift.* 



2 See Notes on the foi-mer existence of the Hippopotamus in Europe, by Mr. 

 Anderson, in the "Eeliquise Aquitanicse," Parts xi. and xii. — Editor. 



* Prof. Henry's resume of Mr. Charles Whittlesey's Notes on the Glacial Drift of the North- 

 western Stijtes. Tiansactions of Smithsonian Institute, 186G, page 35. 



VOL. X — NO. ex. 23 



