THE WANDERINGS OF THE NORTH POLE. 87 



baffled can be removed when note is taken of the drciim stance that the 

 latitude of the observatory is in an incessant condition of transforma- 

 tion in accordance with the law which his labors have expounded. It 

 will ere long be necessary in every observatory Avhere important work 

 is being done to obtain for every day the correction to the mean value 

 of the latitude, in order to obtain the value appropriate for that day. 

 There are also other grounds of a somewhat profounder character 

 on which the discoveries now made are eminently instructive. 

 Those who are interested in the physics of our globe often discuss 

 the question as to whether the internal heat, which the eartli certainly 

 X)ossesses, is sufticiently intense to render the deep seated portions of 

 our globe more or less lluid. On the other hand, the effects of pres- 

 sure, especially of such pressures as are ex})erieDced in tlie depths 

 hundreds and thousands of miles below the surface, must go far to con- 

 solidate the materials to form what must be sensibly a rigid body. 

 The question, therefore, arises: Is the earth to be regarded as a rigid 

 mass, or js it not? The ]>heuomena of the tides had already to some 

 extent afforded information on this subject, and now Mr. Chandler's 

 investigation adds much further light, for it is certain from his result 

 that the earth can not be a rigid body. It is quite true that, even 

 though the earth were rigid, the x)ole might go round in a circle and 

 that circle might have a 30-feet radius, but in such a case the period 

 would be only about three-quarters of the four hundred and twenty- 

 seven days which he has found. In the interest, therefore, of the theo- 

 retical astronomer, as well as on the other grounds Mhich I have set 

 forth, Mr. Chandler's investigations must be regarded as a most impor- 

 tant contribution to modern astronomy. 



