10] 



THE TWO HEADS OF BIELA'S COMET. 



69 



The relative velocities on Feb. 1T5, in the directions of the axes are 

 as follows 



- -3-2647, 





the linear unit being the same as before, and the unit of time a mean 

 solar day. 



From these results it will be easy to deduce the differences of the 



elements of the orbits of the two heads. According to my calculations 



the periodic time of the smaller head is 8 '4 8 days longer than the periodic 

 time of the larger. 



