The Systematic Motions of Sun-spots. 



^and south. The resuUing numbers are given in Table I, which 

 therefore exhibits the distribution of the spot-groups in two ways, 

 the horizontal lines showing the numbers of groups yielding 

 ■different synodic rotation periods, and the vertical columns the 

 number of groups in each zone of latitude 5° Avide. The numbers 

 of Table I are represented graphically in Plate T, a series of curves 

 being drawn, one for each zone. Considering now these curves 

 shown in Plate I, each small circle represents the number of spot- 

 groups corresponding to the given rotation period. They are 

 connected by straight lines, while the heavy continuous lines 

 indicate the smoothed values. 



This Plate shows at a glance that, while there are minor 

 differences between the curves for different zones, yet the main 

 features are repeated in a remarkable way in all six series. We 



