president's address. 843 



ing of surface weights not easy to understand." (Great Ice Age, 

 Note p. 791). 



Sir Charles Lyell considered that all climatic changes could be 

 explained by gradual changes in the distribution of land and 

 water. There are few that now hold this view. It is to be 

 remarked that in Pleistocene times the distribution of land and 

 water was practically the same as now, and yet it was just in 

 that period that the most remarkable oscillations of temperature 

 conditions occur. 



Dr. Geikie in the work already referred to points out that 

 there are oscillations of temperature and rainfall shown hj 

 advance and retreat of glaciers, rising and falling of level of lakes 

 and inland seas, and asks whether these may not be due to cosmic 

 causes, and whether such causes may not have to do with the 

 larger and more extensive oscillations producing giaciation or 

 mild temperatures up to near the pole. 



As regards the question of the geographical shifting of the pole, 

 I find in "Nature," of September 25, ISS-l, a letter by Mr. Flinders 

 Petrie referring to an Address by Professor Young, which stated 

 that a change of one second per century had been noted at Palkowa 

 in the earth's axis. Other corroborations of the same fact exist. 

 He says : — " Such a change might be effected by causes which 

 are beyond our observation ; as, for instance, unbalanced ocean 

 circulation equal to a ring of water only 4 square miles in section 

 moving at a mile an hour across the poles." Mr. Petrie refers to 

 the Gizeh Pyramids ; these structures, the errors of which are 

 but a few seconds of angle, agree in standing as much as 4' or 5' 

 to the west of the present north. 



Professor Newcomb some years ago, from observations of the 

 transit of Mercury, concluded that the rotational period of the 

 earth was not a fixed quantity, and it has since been amply shown 

 from the study of the same phenomena that the period is subject 

 to variation, increasing for a number of years and then diminish- 

 ing again, and so on. I do not know whether any explanation 

 has been offered of this phenomenon, but may it not indicate 



