ON DISPLACEMENTS OF THE ROTATIONAL AXIS OF THE EAKTH. 479 



This sketch is founded on nearly 6,000 single determinations of latitude 

 made in the Observatory of Kasan (Eastern Russia), Strassburg, Elsass 

 (41° 21' west of Kasan), and Bethlehem, Pennsylvania (124° 30' west of 

 Kasan). The observations are condensed in twenty monthly mean results, 

 numbered from zero to 1 9. Every one of these resulting monthly positions 

 of the pole indicated by the centres of the small circles is thus tho 

 mean result of about 300 single determinations. 



o6 



Figure showing movement of tlie North Pole of the rotational axis of the earth. 

 Derived from observations made at Betlilehem, Strassburg, and Kasan : — 



0=1892 Oct. 20. 

 1 = „ Nov. 1. 

 2= „ Dec. 1. 

 3=1893 Jan. 1. 



13 = 1893 Nov. 1. 

 14= ., Dec. 1. 

 15 = 1894 Jan. 1. 



19 = 1894 May 1. 



The figure is drawn on the scale of 



two millimetres to one-hundredth 

 of a second of arc, and the maximum amplitude of the curve is nearly 

 tifty-hundredths, or half a second. The amplitude of these movements of 

 the pole on the surface of the earth is between 40 and 50 feet. 



The general character of the movement is quite in accordance with 

 what has been mentioned concerning its complicated and somewhat spiral 



