34 Rkpout S.A.A. Advanckment of Science. 



(3) There is a tliinl possible explanation of the recession of ji 

 Lyrae and V Puppis. 



Prof. Sehaeberle of Ann Arbor University suggests that " an 

 incandescent bod\' has the power to remove a part of its mass, in a 

 finely divided state, to great distances, even beyond the sphere of its 

 own sensible attraction. At a certain stage in the life-history of such 

 a body the decrease in mass may be so rapid as to produce a sensible 

 increase in the periodic time of any body belonging to the system." 



The standing of Prof. Schaeberle, as well as the reasonableness of 

 the explanations, compels our consideration. And fortunately we are 

 able to bring to bear upon the theory a numerical test of a very simple 

 character. 



Thus let M^, and Mj be the masses of any binary system at any 

 two widely separate dates, and T,, and T^ the periods of tlie system at 

 these two dates, then 



Now if A '« = the loss in the mass according to Prof. Schaeberle's 



hypothesis, 



and \t :^ the increment in time, 



A m 2 A t 

 then ^rp = -^—- 



Take first the case of (i Lyrae, and let it be reijuire;! to ascertain 

 the diminution in mass during one hundred years. 

 Here we have the following relation— - 



A m 90"' 



M^ 18549'" 

 - -0018.5 



That is to say, if Pi'of. fSchaeberle's theory 1)0 sustained, S Lvrao 

 has parted with the five-thousandth part of its mass during th(» past 

 hundred years. 



Weight, of course, must be given to the important addendum by 

 Prof. Scliaeberle to his general contention, viz., that "at a certain 

 stage in the life liistory of such a body the decrease in mass may be 

 so i-apid as to produce a sensible increase in the periodic time." 



In other words, at an early stage; in the life history of the star it 

 parted readily with portions of its mass, and the increase in pei'iod 

 was correspondingly rapid. This shedding of}' process, however, was 

 not sustained at the same rate, and consequently we ha\e the decline 

 in the acceleration of period which is such a marked feature in the 

 case of /3 Lyrae. 



Granting, however, the reasonableness and simplicity of this ex- 

 planation, it does not completely convince. It seems to me that the 



