VARIATION OF LATITUDE. 



279 



divergencies are very small, ouly 14 millimeters, equal to one-half 

 iucb about, but tbey appear unmistakably and are what theory would 



demand. _ , ^ ^ ., ^ i 



In a letter, recently received from Dr. Chandler, he states that he 

 finds that the annual part of the polar motion is an ellipse three or four 

 times as long as broad, and he expresses the law of the motion of the 

 pole in this ellipse as that the areas described from the center are pro- 

 portional to the times. . . ^.^ i 



We can conclude safely, therefore, that no large changes of latitude 

 have taken place for many thousands of years; in fact, m geologic 

 times that there is no adequate proof of progressive changes in the 

 latitude of any place ; but, finally, that very small periodic changes have 

 occurred, and they are ^uch as can be and are observed. 



Tlie feeling is growing in the minds of those who have given the sub- 

 ject close attention that we shall find that many and various causes 

 enter into the problem of determiniug the law of changes. It wdl no 

 doubt take many years of careful observation to obtain the data neces- 

 sary to fully test Dr. Chandler's, or any other hypothesis. 



The scientific men abroad are discussing the advisability of estab- 

 lishing several observatories at various places on the earth's surface 

 for the purpose of collecting the data. 



Ultimately Dr. Chandler's formula, or a slight modification of it, may 

 be proved correct, and with it we may be able to state what the lati- 

 tude of any place will be at auy time. 



The lecture was followed by some illustrations showing that revolving 

 bodies preferred to revolve about their shortest axis or around the axis 

 about which the moment of inertia was a maximum. 



Charts and diagrams were exhibited showing the results of obser- 

 vations made at Pulkova, Prague, Berlin, Strasburg, Bethlehem, the 

 Sandwich Islands, etc. 



These results were compared with the deductions from Chandler s 

 formula and shown to agree therewith to a remarkable extent. 



The preliminary results of the observations made at Columbia- Col- 

 lege from May, 1893, to July, 1891, were exhibited. 



The lecturer threw on the screen illustrations of several forms ot 

 zenith telescopes, and described the new form made by Wanschafl, of 

 Berlin. 



