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Kansas Academy of Science. 



were the smallest, those of Berlin were the largest ; that is to say, if 

 the north pole moved nearer America, it must move further from 

 Europe ; and, on the other hand, if further from America, then 

 nearer Europe. There was something perplexing about these 

 movements, as they had been known for a long time, but no satis- 

 factory solution had been given. Mr. Chandler solved the problem, 

 and the difficulties were removed. 



To show that there is a deviation of the earth's pole from its 

 average position, two" tables, prepared by Chandler, showing the 

 distances of the earth's pole, in feet, from its average position, are 

 herewith given, each representing a year's observations. The signs 

 plus and minus indicate opposite directions of displacement. The 

 first table was made at Washington, D. C, and the other at Pulkowa, 

 near St. Petersburg. 



Washington. 



December, 1864 -28 feet. 



March, 1865 - 1 



June, 1865 +15 



August, 1865 +22 



October, 1865 +11 



December, 1865 —17 



Pulkowa. 



July, 1865.... -18 feet. 



September, 1865 +3 



November, 1865 +26 



February, 1866 +18 



June, 1866 -11 



July, 1866 -16 



The figures are not exact in every case, but the error in them is 

 always a very small one. Every expert astronomical observer knows 

 how difficult a matter it is to obtain the position of the earth's pole 

 to within a foot. 



Mr. Chandler's investigation of the results reached by other astron- 

 omers, and comparing them with his own, arrived at the conclusion 

 that there was, besides the vibration of the earth's axis in the body 

 of the earth, also an increase in the period of polar revolution. At 

 the time of Bradley's observations the period was shorter by about 

 two months than it is now. Whether this movement is subject to a 

 periodicity, reaching at one time a maximum and then a minimum, 

 is not yet determined. But it is certainly known that at times 

 there are very irregular movements, due to some cause or other, 

 followed by others that are subject to a periodicity. 



Chandler says : "Another characteristic which has struck my at- 

 tention, although somewhat vaguely, is that the variations in the 

 length of the period seem to go hand in hand with simultaneous 

 alterations in the amplitude of the rotation ; the shorter periods 

 being apparently associated with the larger coefficients for the 

 latter." 



Almost all of the series of observations of any extent which 



