19 



DIFFICULTIES IN PREVIOUS EXPLANATIONS. 



The postulates and corollaries just given appear to 

 the author to satisfactorily account for the great varia- 

 tions in climate geologically recorded in the history of 

 our planet. The difficulties met with in previous at- 

 tempts to explain present, glacial and pre-glacial climates 

 have been due in part to a failure to give due weight to 

 certain of the laws which are above cited, and to fully 

 recognize the force of others. For instance: 



(1) The influence and functions of water in its various 

 forms upon the mode and rate of loss of planetary heat 

 have not been given due weight. 



(2) The effect of the difference in the specific heat 

 of land and water has been omitted in most of the dis- 

 cussions. 



(3) The conservative function of solar energy prior 

 to the exhaustion of planetary heat has not been fully 

 recognized. 



(4) The ultimate influence of the trapping of solar 

 energy in the lo^wer layers of the atmosphere, and the 

 cumulative effect of this action upon surface tempera- 

 tures has been left out of consideration. 



(5) That the acceptance of ice action alone as proof 

 of a glacial epoch is not warranted. 



The failure to fully weigh and adjust the effects of the 

 laws of climatic evolution has almost necessitated a re- 

 sort to assumptions and hypotheses, some of which have 

 been of a vague and indefinite nature, and others rest 

 upon an inadequate foundation. Of these may be 

 cited: Variations in the amount of solar energy, in 

 the heat absorbing power of the solar atmosphere, in the 

 temperature of space, in the direction and temperature 

 of the Gulf Stream, in the elevations and depressions 



